WO2022029703A1

WO2022029703A1 - Agricultural method and device

Info

Publication number: WO2022029703A1
Application number: PCT/IB2021/057238
Authority: WO
Inventors: Warrick David CATTO; Aaron David Stafford
Original assignee: Ballance Agri-Nutrients Limited
Priority date: 2020-08-07
Filing date: 2021-08-06
Publication date: 2022-02-10

Abstract

The present invention relates to a method for determining the responsiveness of an area of grazed forage to one or more nutrients, a pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients and/or the use of the sensor and/or the method to generate a prescription for the application of one or more chemicals to the area of grazed forage. The present invention further or alternatively relates to a method of applying one or more nutrients to an area of grazed forage and/or a method of applying nitrogen fertiliser to an area of grazed forage. In particular, the invention makes use of excrement/urine patch(s) to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

Description

AGRICULTURAL METHOD AND DEVICE

FIELD OF THE INVENTION

[0001] The present invention relates to a method for determining the responsiveness of an area of grazed forage to one or more nutrients, a pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients and the use of the sensor or method to generate a prescription for the application of one or more chemicals to the area of grazed forage. The present invention further or alternatively relates to a method of applying one or more nutrients to an area of grazed forage and/or a method of applying nitrogen fertiliser to an area of grazed forage In particular, the invention makes use of excrement/urine patch(s) to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

BACKGROUND TO THE INVENTION

[0002] The effective management of inter and intra-field soil and crop conditions is essential to maximise the productivity of farms. The concept of precision farming recognises that different areas of a land may have different potentials and aims to tailor treatment to maximise potential while at the same time limiting costs.

[0003] Pasture nitrogen responsiveness is one soil parameter whose potential may vary greatly across different areas of land. An accurate prediction of the nitrogen responsiveness of different areas of grazed pasture would allow farmers to apply sufficient fertiliser to achieve maximum crop potential for a particular area and limit over application of fertilizer which can be costly and detrimental to the environment.

[0004] Some techniques for predicting the crop yield potential of areas of a farm and applying nutrients, such as nitrogen fertiliser, based on such predictions are already known in the art. However, these techniques are time consuming to implement. As such the commercial applicability of many of these techniques remains limited.

[0005] There remains a need for improved techniques to determine the nutrient responsiveness of different areas of grazed forage/ pasture.

[0006] In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

SUBSTITUTE SHEET (RULE 26) [0007] It is an object of the present invention to provide a method for determining the responsiveness of an area of grazed forage to one or more nutrients and/or a pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients and/or a device comprising the pasture sensor. Additionally or alternatively it is an object of the present invention to provide use of the pasture sensor and/or the device and/or the method to generate a prescription for the application of one or more chemicals to the area of grazed forage. Additionally or alternatively it is an object of the present invention to provide a method of applying one or more nutrients to an area of grazed forage and/or a method of applying nitrogen fertiliser to an area of grazed forage. Additionally or alternatively it is an object of the present invention to at least provides the public and/or industry with a useful choice.

[0008] Other objects of the invention may become apparent from the following description which is given by way of example only.

SUMMARY OF THE INVENTION

[0009] In a first aspect the present invention relates to a method for determining the responsiveness of an area of grazed forage to one or more nutrients, the method comprising the steps of a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral measurements from the at least one excrement patch and the at least one inter-excrement patch, and c) interpreting the difference in the spectral measurement from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

[0010] In some embodiments the one or more nutrient is present in excrement. In some embodiments the nutrient is nitrogen or potassium. In some embodiments the nutrient is nitrogen.

[0011] In some embodiments the excrement is urine. In some embodiments the excrement patch is a urine patch. In some embodiments the inter-excrement patch is an inter-urine patch.

[0012] In some embodiments the difference in the spectral measurements from the at least one excrement/urine patch and the at least one inter-excrement/urine patch is interpreted by an algorithm to determine the potential responsiveness of the area of grazed forage to the one or more nutrients. [0013] In some embodiments at least two spectral measurements are taken from the at least one excrement/urine patch. In some embodiments at least three spectral measurements are taken from the at least one excrement/urine patch. In some embodiments at least four spectral measurements are taken from the at least one excrement/urine patch. In some embodiments at least five spectral measurements are taken from the at least one excrement/urine patch.

[0014] In some embodiments between 2 and 50 spectral measurements are taken from at least one excrement/urine patch. In some embodiments between 2 and 40 spectral measurements are taken from at least one excrement/urine patch. In some embodiments between 2 and 30 spectral measurements are taken from at least one excrement/urine patch. In some embodiments between 2 and 20 spectral measurements are taken from at least one excrement/urine patch. In some embodiments between 2 and 15 spectral measurements are taken from at least one excrement/urine patch. In some embodiments between 2 and 10 spectral measurements are taken from at least one excrement/urine patch. In some embodiments between 2 and 5 spectral measurements are taken from at least one excrement/urine patch.

[0015] In some embodiments at least two spectral measurements are taken from more than one excrement/urine patch, with each spectral measurement taken from a different excrement/urine patch. In some embodiments at least two spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments at least three spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments at least four spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments at least five spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch.

[0016] In some embodiments between 2 and 50 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments between 2 and 40 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments between 2 and 30 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments between 2 and 20 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments between 2 and 15 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments between 2 and 10 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments between 2 and 5 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch.

[0017] In some embodiments at least two spectral measurements are taken from at least one inter-excrement/urine patch. In some embodiments at least three spectral measurements are taken from at least one inter-excrement/urine patch. In some embodiments at least four spectral measurements are taken from at least one inter- excrement/urine patch. In some embodiments at least five spectral measurements are taken from at least one inter-excrement/urine patch.

[0018] In some embodiments at least two spectral measurements are taken with the spectral measurements being taken from more than one inter-excrement/urine patch. In some embodiments at least three spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments at least four spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch. In some embodiments at least five spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch.

[0019] In some embodiments between 2 and 50 spectral measurements are taken, with the spectral measurements being taken from more than one inter-excrement/urine patch. In some embodiments between 2 and 40 spectral measurements are taken from more than one inter-excrement/urine patch. In some embodiments between 2 and 30 spectral measurements are taken from more than one inter-excrement/urine patch. In some embodiments between 2 and 20 spectral measurements are taken from more than one inter-excrement/urine patch. In some embodiments between 2 and 15 spectral measurements are taken from more than one inter-excrement/urine patch. In some embodiments between 2 and 10 spectral measurements are taken from more than one inter-excrement/urine patch. In some embodiments between 2 and 5 spectral measurements are taken from more than one inter-excrement/urine patch.

[0020] In some embodiments where more than one spectral measurement is taken from the at least one excrement/urine patch the average of the spectral measurements is used to quantify the difference in the spectral measurements in step b).

[0021] In some embodiments where more than one spectral measurement is taken from the at least one inter-excrement/urine patch the average of the spectral measurements is used to quantify the difference in the spectral measurements in step b).

[0022] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly on the same or similar soil type. [0023] In some embodiments the forage is selected from any one or more of a grass, an herbaceous legume, crop residue, lucerne, forage brassicas, for example swede, turnip or kale, cereal crops, cover crops.

[0024] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly the same forage type (for example, both grasses).

[0025] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly both the same genus of forage plant.

[0026] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly the same species of forage plant.

[0027] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly forage plants with the same number of chromosomes.

[0028] In some embodiments the excrement/urine patch and the inter- excrement/urine patch of the grazed forage are predominantly grasses.

[0029] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly grasses with the same number of chromosomes.

[0030] In some embodiments the excrement/urine patch and the inter- excrement/urine patch are predominantly diploid grasses. In some embodiments the excrement/urine patch and the inter-excrement/urine patch are predominantly tetrapioid grasses.

[0031] In some embodiments substantially the whole area of grazed forage has been managed in substantially the same way.

[0032] In some embodiments the spectral measurement is measurement of light.

[0033] In some embodiments the spectral measurement is selected from one or more of measurement of red light, green light, infrared light.

[0034] In some embodiments the method further includes the step of obtaining at least one spectral measurement from a reference.

[0035] In some embodiments the difference in the spectral measurement from the at least one excrement/urine patch, the at least one inter-excrement/urine patch and the reference is interpreted to determine the yield potential of the area of grazed forage.

[0036] In some embodiments the spectral measurement is done with a camera or imaging device. [0037] In some embodiments the spectral measurement is taken with a digital multispectral camera or Active Light Source optical sensor.

[0038] In some embodiments the spectral measurement is taken with a digital camera.

[0039] In some embodiments the spectral measurement is taken with a smart phone camera, satellite or aerial vehicle.

[0040] In some embodiments the spectral measurement from at least one excrement/urine patch and the at least one inter-excrement/urine patch are done within at least about 12 hours of each other. In some embodiments the spectral measurement from at least one excrement/urine patch and the at least one inter-excrement/urine patch are done within at least about 8 hours of each other. In some embodiments the spectral measurement from at least one excrement/urine patch and the at least one inter- excrement/urine patch are done within at least about 6 hours of each other. In some embodiments the spectral measurement from at least one excrement/urine patch and the at least one inter-excrement/urine patch are done within at least about 3 hours of each other. In some embodiments the spectral measurement from at least one excrement/urine patch and the at least one inter-excrement/urine patch are done within at least about 2 hours of each other. In some embodiments the spectral measurement from at least one excrement/urine patch and the at least one inter-excrement/urine patch are done within at least 1 hour of each other.

[0041] In some embodiments the spectral measurement of the at least one excrement/urine patch and the at least one inter-excrement/urine patch are obtained at the same time.

[0042] In a second aspect the present invention relates to a pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients, the sensor comprising a detector for detecting spectral signals from at least one excrement patch and at least one inter-excrement patch, and a processor for quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch, wherein the processor interprets the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

[0043] In some embodiments the one or more nutrient is present in excrement. In some embodiments the nutrient is nitrogen or potassium. In some embodiments the nutrient is nitrogen. [0044] In some embodiments the excrement patch is a urine patch. In some embodiments the inter-excrement patch is an inter-urine patch.

[0045] In some embodiments the processor uses an algorithm to interpret the difference in the spectral signals from the at least one excrement/urine patch and the at least one inter-excrement/urine patch to determine the yield potential of an area of grazed forage.

[0046] In some embodiments the sensor is a camera or imaging device.

[0047] In some embodiments the processor calculates an average of the spectral signals from the at least one excrement patch.

[0048] In some embodiments the processor calculates an average of the spectral signals from the at least one inter-excrement patch.

[0049] In some embodiments the processor interprets the difference in an average of spectral signals from the at least one excrement patch and an average of spectral signals from the at least one inter-excrement patch.

[0050] In a third aspect the present invention relates to a device comprising a pasture sensor according to the second aspect.

[0051] In some embodiments the device is a mobile phone, camera or imaging device.

[0052] In a fourth aspect the present invention relates to the use of the pasture sensor according to the second aspect, the device according to the third aspect or the method according to the first aspect to generate a prescription for the application of one or more chemicals to the area of grazed forage.

[0053] In various embodiments the one or more chemicals according to the fourth aspect is selected from one or more of a nitrogen source, potassium source, phosphate source, urease inhibitor, denitrification inhibitor, plant growth regulator, hormone, biostimulant, fertiliser and lime.

[0054] In exemplary embodiments the one or more chemicals according to the fourth aspect is selected from one or more of a nitrogen source, phosphate source and potassium source. In exemplary embodiments the one or more chemicals according to the fourth aspect is selected a nitrogen source.

[0055] In a fifth aspect the present invention relates to a method of applying one or more nutrients to an area of grazed forage, the method comprising the steps of: a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch, c) interpreting the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients, and d) applying an amount of the one or more nutrients to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one excrement patch and the at least one inter-excrement patch, wherein the larger the difference the more of the one or more nutrients is applied.

[0056] In a sixth aspect the present invention relates to a method of applying nitrogen fertiliser to an area of grazed forage, the method comprising the steps of: a) obtaining at least one spectral measurement from at least one urine patch and at least one inter-urine patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch, c) interpreting the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch to determine the potential responsiveness of the area of grazed forage to nitrogen fertiliser, and d) applying an amount of the nitrogen fertiliser to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one urine patch and the at least one inter-urine patch, wherein the larger the difference the more nitrogen fertiliser is applied.

[0057] For the avoidance of doubt the embodiments of the first aspect may also apply alone or in any combination of two or more thereof to any one of more of the second, third, fourth, fifth and sixth aspects where context allows.

[0058] Any of the aforementioned features or embodiments or aspects may be combined with one or more of the other features or embodiments or aspects as described herein.

[0059] The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. [0060] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[0061] As used herein the term "and/or" means "and" or "or", or both.

[0062] As used herein "(s)" following a noun means the plural and/or singular forms of the noun.

[0063] To those skilled in the art to which the invention relates, many changes in construction and differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

[0064] The disclosure consists in the foregoing and also envisages constructions of which the following gives examples only. Features disclosed herein may be combined into new embodiments of compatible components addressing the same or related inventive concepts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The invention will now be described by way of example only and with reference to the drawings in which:

[0066] Figure 1 shows NDVI-values from the Green Seeker - the relationship between yield response to N fertiliser (average of 50 and 100 kg N/ha rates) at harvest 1 and calculated delta colour for harvest 1 (left) or harvest 2 (right).

[0067] Figure 2 shows data from the Tec-5 - the relationship between yield response to N fertiliser (average of 50 and 100 kg N/ha rates) at harvest 1 and calculated 'delta colour' (strictly, delta simple-ratio) for harvest 1 (left) or harvest 2 (right).

[0068] Figure 3 shows data from the Smartphone - the relationship between yield response to N fertiliser (average of 50 and 100 kg N/ha rates) at harvest 2 and calculated delta colour for harvest 1 using two different wavelengths.

[0069] Figure 4 shows comparative data using dry matter measures to calculate delta yield. DETAILED DESCRIPTION OF THE INVENTION

[0070] The present invention relates to providing a method, and/or a pasture sensor and/or a device for determining the responsiveness of an area of grazed forage to one or more nutrients. The method, pastor sensor and/or device can be used to generate a prescription for the application of the one or more chemicals to the area of grazed forage and/or as part of a method of applying one or more chemicals to the area of grazed forage.

[0071] In one aspect the present invention provides a method for determining the responsiveness of an area of grazed forage to one or more nutrients, the method comprising the steps of a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral measurements from the at least one excrement patch and the at least one inter-excrement patch, and c) interpreting the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

[0072] The present invention also or alternatively provides a pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients, the sensor comprising a detector for detecting spectral signals from at least one excrement patch and at least one inter-excrement patch, and a processor for quantifying the difference in the spectral signals from the at least one excrement patch and the at least one interexcrement patch, wherein the processor interprets the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

[0073] The present invention also or alternatively provides a device comprising the pasture sensor.

[0074] The present invention also or alternatively provides use of the pasture sensor, the device or the method to generate a prescription for the application of one or more chemicals to the area of grazed forage.

[0075] The present invention also or alternatively provides a method of applying one or more nutrients to an area of grazed forage, the method comprising the steps of a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch c) interpreting the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients, and d) applying an amount of the one or more nutrients to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one excrement patch and the at least one inter-excrement patch, wherein the larger the difference the more of the one or more nutrients is applied.

[0076] In some embodiments the excrement is urine, the excrement patch is a urine patch and/or the inter-excrement patch is an inter-urine patch. The main nutrient provided by urine is nitrogen, the one or more nutrients is therefore preferably nitrogen, however, other nutrients such as potassium are also present in animal excrement, particularly urine. The invention may therefore be applied to an area of grazed forage which is responsive to addition of nitrogen or potassium or other nutrients or decomposition products of nutrients in animal excrement, particularly in animal urine. The area of grazed forage will generally be responsive to addition of one or more nutrient(s) when it is deficient in the one or more nutrient(s).

[0077] The present invention also or alternatively provides a method of applying nitrogen fertiliser to an area of grazed forage, the method comprising the steps of a) obtaining at least one spectral measurement from at least one urine patch and at least one inter-urine patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch, c) interpreting the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch to determine the potential responsiveness of the area of grazed forage to nitrogen fertiliser, and d) applying an amount of the nitrogen fertiliser to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one urine patch and the at least one inter-urine patch, wherein the larger the difference the more nitrogen fertiliser is applied.

Excrement/Urine patch

[0078] Excrement/urine patches occur naturally when forage is grazed. The animal excrement includes faeces and/or urine from the animal that have previously grazed or are currently grazing the forage. Using the patch(es) to determine the responsiveness of an area of grazed forage to one or more nutrients is therefore a convenient and cost effective. The method/device/sensor allows for responsiveness to be tested without the inconvenience of preparing a test strip. It is very beneficial to test for responsiveness as this can avoid the use or overuse of nutrients without seeing significant benefits. Overuse can be detrimental to the environment if excess nutrients run off into a water course.

[0079] Urine patches are particularly preferred for use in the invention, as the urine generally does not sit on the surface which may affect the spectral measurement. A urine patch typically has a nitrogen content of about 600 kg N/ha (see for example Selbie et al., D.R., Buckthought, L.E., Shepherd, M.A. (2015). The challenge of the urine patch for managing nitrogen in grazed pasture systems. Advances in Agronomy 129. 2015) and potassium content of from 180 to over 500 kg K/ha. An excrement or urine patch used for the purposes of this invention can therefore be considered to be a patch of pasture/forage that has had a nitrogen solution and/or potassium solution voided that has a nitrogen content the equivalent of 500 kg N/ha or more and/or a potassium content of 180kg K/ha or more where the nitrogen and/or potassium content has at least in part been provided by animals urinating/defecating on the patch. A urine/excrement patch is usually apparent and identifiably to the skilled person by the difference in height and/or density of growth and/or colour (in particular darkness of green colour) of the patch compared to other (inter- excrement/urine patch) sections of the grazed forage. The typical average size of a urine/excrement patch is about 0.35 m², but can be larger or smaller. An area of grazed forage will typically have a mosaic of urine patches, which are typically 5-10% of the area of the grazed forage.

[0080] The present methods/sensor/device allow farmers to reduce the amount of nutrients (particularly nitrogen fertiliser) applied to forage land while maintaining forage/pasture growth, by providing greater precision of nutrient application by identifying and targeting specific zones (for example fields/areas with low soil nitrogen).

Spectral measurement of patches

[0081] When spectral measurements are taken it is preferable to take measurements from different excrement/urine patches and/or different inter-excrement/urine patches within the area of grazed forage in order to compare the average of the excrement/urine patches and/or the average of the inter-excrement/urine patches, for example the mean or the mode can be used. Where measurements are taken from multiple inter-excrement patches, it is preferable that the patches are spaced over the area of grazed forage, in order to get a representative sample.

[0082] Multiple measurements can also be taken from the same excrement/urine patch and the average spectral measurement calculated and/or the same inter-excrement/urine patch and the average spectral measurement calculated. The number of spectral measurements taken will vary with the size of the area of grazed forage and/or the number of excrement/urine patches available and/or identified.

[0083] In some embodiments, at least two, at least three, at least four or at least five spectral measurements are taken from the at least one excrement/urine patch. In some embodiments about 2-50, 2-40, 2-30, 2-20, 2-15, 2-10, or 2-5 spectral measurements are taken from at least one excrement/urine patch. [0084] In some embodiments at least two spectral measurements are taken from more than one excrement/urine patch with each spectral measurement taken from a different excrement/urine patch. In some embodiments at least two, three, at least four, or at least five spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch.

[0085] In some embodiments between about 2 and 50, 2 and 40, 2 and 30, 2 and 20, 2 and 15, 2 and 10, or 2 and 5 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch.

[0086] In some embodiments at least two, at least three or at least four spectral measurements are taken from at least one inter-excrement/urine patch.

[0087] In some embodiments at least two, at least three, at least four, or at least five spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch.

[0088] In some embodiments between about 2 and 50, 2 and 40, 2 and 30, 2 and 20, 2 and 15, 2 and 10, or 2 and 5 spectral measurements are taken from more than one inter- excrement/urine patch. However, it will be apparent to a person skilled in the art the number of spectral measurements taken will depend on the size of the area of grazed forage.

Area of grazed forage

[0089] The at least one excrement/urine patch and at least one inter-excrement/urine patch are both smaller areas within the area of grazed forage.

[0090] The forage is any crop which has been or is planted in an area where urine/excrement patches are present/visible. The forage may be selected from any one or more of a grass, an herbaceous legume, crop residue, lucerne, forage brassicas, for example swede, turnip or kale, cereal crops, cover crops.

[0091] It is preferable that the excrement/urine patch and the inter-excrement/urine patch in the area of grazed forage are predominantly on the same or similar soil type and/or are predominantly the same type of forage plant and/or the same genus of forage plant and/or the same species of forage plant and/or have the same number of chromosomes. Where the forage is grasses, preferably they are predominantly grasses with the same number of chromosomes, for example predominantly diploid grass or tetrapioid grass. For example, where there are areas of different soil or forage plants these can be considered a different area of grazed forage and the spectral measurements can be completed within that area. [0092] It is further preferable that the area of grazed forage the measurements are taken from (excrement/urine patch(s) and inter-excrement/urine patch(s)) has been managed in substantially the same way across substantially the whole area, for example the grazing management, spelling period, fertiliser use, and/or irrigation practices.

[0093] Reference to "predominantly' or similar within this specification can be considered to mean more than about 60% or more than about 70% or more than about 80% or more than about 90%, or more than about 95%.

[0094] The invention is also or alternatively related to the use of the pasture sensor or the device or the method of the invention to generate a prescription for the application of one or more chemicals to the area of grazed forage. The one or more chemicals may be selected from one or more of a nitrogen source, a potassium source, a phosphate source, a urease inhibitor, a denitrification inhibitor, a plant growth regulator, a hormone, a biostimulant, a fertiliser or lime, preferably a nitrogen source, a phosphate source or a potassium source, preferably a nitrogen source.

Spectral measurements

[0095] The spectral measurements or the measurement of spectral signals is the measurement of light, preferably selected form one or more of red light, green light, infrared light.

[0096] The spectral measurement is preferably done with a camera or imaging device, for example a digital multispectral camera, Active Light Source optical sensor or a digital camera. In a particularly preferred embodiment, the spectral measurement is taken with a smart phone camera. A smart phone is small, convenient, has a camera and has processing capability to quantify and interpret the spectral measurements. The spectral measurements may be taken from a satellite or aerial vehicle, such as a drone or manned aircraft.

[0097] The spectral measurement of the patches may be done for each patch individually.

[0098] It is preferred that the measurement from at least one excrement/urine patch and the at least one inter-excrement/urine patch are done within a relatively short time of each other, for example at least about 12 hours of each other, least about 8 hours, at least about 6 hours, at least about 3 hours, at least about 2 hours, at least about 1 hour. This reduces the differences in the growth of the excrement/urine patch and inter- excrement/urine patches attributable to other reasons (for example season or rainfall) and/or can reduce the chances of different light conditions, for example, cloud cover or time of day. [0099] Alternatively, the spectral measurements of the at least one excrement/urine patch and the at least one inter-excrement/urine patch are obtained at the same time, for example in the same image/measurement of the whole or part of the area of grazed forage. The excrement/urine patches and/or the inter-excrement/urine patches are then identified within the measurement/image. The excrement/urine patches and/or the inter- excrement/urine patches may be identified manually or automatically, for example with an algorithm, or other means which identifies patches with a different spectral measurement.

[OO1OO] The spectrum measurements can be compared to a pre-prepared reference, for example a card with known coloured areas. This can be used to calibrate the spectral measurement(s) from the excrement/urine patch and/or the inter-excrement/urine patches. However, this is may be less convenient for the user. It is also considered that as it is the difference in the spectral measurements from the at least one excrement/urine patch and the at least one inter-excrement/urine patch that is quantified (for example the ratio), a separate reference may not be required.

[00101] Positioning data, for example geopositioning data, may also be taken/recoded when the spectral measurements are taken. Positioning data may be useful to verify to a regulator or other party the practice of applying the one or nutrients was appropriate or for example to claim carbon credits other benefits.

[00102] Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth.

[00103] Although the present disclosure has been described in terms of certain embodiments, other embodiments apparent to those of ordinary skill in the art also are within the scope of this disclosure. Thus, various changes and modifications may be made without departing from the spirit and scope of the disclosure. For instance, various components may be repositioned as desired. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present disclosure. Accordingly, the scope of the present disclosure is intended to be defined only by the claims that follow.

EXAMPLES

[00104] A study was conducted on grass sward plots in Hamilton, New Zealand. Nitrogen fertiliser was applied as (a) slow release fertiliser to simulate mid-term effects of urine from cows grazing the pasture and (b) regular N fertiliser to assess the response of additional N onto non-urine or urine-areas of the pasture. Fertiliser Application Rates

[00105] The plots were fertilised with a slow release N fertiliser (referred to as "Background N") on four levels: (i) 0 kg N/ha, (ii) 100 kg N/ha, (iii) 200 kg N/ha, (iv) 400 kg N/ha and with regular N fertiliser (referred to as "Treatment N") on five levels: (i) 0 kg N/ha, (ii) 50 kg N/ha, (iii) 100 kg N/ha, (iv) 600 kg N/ha. The Background N and Treatment N were used in 20 nitrogen treatment combinations on 88 pasture plots.

Sensors

[00106] The following sensors were tested:

I. Digital multispectral camera (JAI AD-080 GE) with sensors for (i) Red, Green & Blue (RGB) and (ii) for Near Infrared (NIR) reflectance to capture images of the swards from above.

II. Active Light Source optical sensor (ALS from Yara/Tec-5), with a four N specific channels, to assess standard crop reflectance indices: Simple Ratio and Water Index.

III. Active Light Source optical sensor (GreenSeeker from Trimble) to provide reflectance index Normalised Difference Vegetation Index (NDVI)

IV. Smartphone camera (Samsung Galaxy S6) to calculate the green chromaticity

[00107] The Normalized Difference Vegetation Index (NDVI) is a numerical vegetation index that uses the visible and near-infrared bands of the electromagnetic spectrum and is adopted to estimate plant vigour using remote sensing measurements.

[00108] Data was acquired with these technologies and geo-referenced with RTK-GPS receiver (Model RIO, Trimble Navigation Limited, Sunnyvale, California, USA) to assess reflectance data and provide calculated indices that are linked to N content, greenness and plant vigour. The RTK-GPS receiver provides highly accurate (+/- 2 cm) geopositions for merging the positions with the data from the sensor measurements.

[00109] Table 1 gives an overview and technical specifications of the sensors used for sensing the pasture swards.

[00110] Table 2 gives an overview and technical specifications of how the sensors were set up. For the GreenSeeker and the Smartphone camera the readings/images were distributed across long axis, middle of plots.

[00111] At each plot, separate software was used to capture the necessary data which included NIR and RGB colour images (JAI) and N content along with GPS coordinates (Yara/tec5). Driving (pushing/pulling) of the rig was accomplished at approximately 0.5 m/s speed.

Table 1

Table 2

Dry Matter Measurement Methods [00112] For comparison with the sensor data, pasture dry matter (DM) was measured from each plot the day after the sensor measurements. Pasture dry matter was harvested from each plot about every 3 weeks with a hand mower cutting to a uniform height of about 50 mm. The total fresh matter was removed from the plot, weighed in the field, and a subsample of about 150-200 g was collected. Each sub-sample was weighed in the laboratory before being oven-dried at 65°C for 48 hrs. Once dried, the sub-samples were then reweighed to calculate pasture dry matter (DM) yield (kg/ha). Three harvests were made approximately 1 month apart. Analysis of Data

[00113] Pasture DM yield was calculated using the weight measurements collected from each harvest. Pasture response to fertiliser N (kg DM/kg N, dry mass per kg of nitrogen supplied by the fertiliser) for the 50 and 100 kg N/ha rates ('farm application rates') was calculated for each background N supply using the formula:

Response to N (kg DM/kg N) = (DMNfert - DMnii)/Nfert

[00114] Two indicators of pasture response were also calculated:

1. "Delta yield" - the difference in yield between 600N (mimic of urine patch) and nil-N for each background N supply

2. "Delta colour" - the difference in a colour estimate (as measured by each sensor) between 600N (mimic of urine patch) and nil-N for each background N supply

[00115] Statistical analysis was carried out using GenStat 16.2 to test statistical significance of response and growth rate between the differential background soil N supply and applied fertiliser rates. Regression analysis was used to test for relationships between response and pasture properties.

Results

[00116] The fertiliser response between Treatment N 50 and 100 kg N/ha did not always show a significant DM difference, so "Delta yield" was used, i.e. the difference in yield between 600N (mimic of urine patch) and nil-N for each background N supply, rather than comparing all the different Treatment N rates.

[00117] Table 3 shows the delta colour measures for the different sensors compared to delta yield.

[00118] Theoretically, the delta values should decrease with increasing background N, as the difference between the background N and the "urine patch" (600N) should be less.

[00119] With reference to Table 3, the NDVI-values from the Green Seeker clearly showed the NDVI-differential decreasing with background N supply, with this same trend at both harvests. The other three technologies also generally showed the same trend but had some outlying values.

[00120] Of the wavelengths tested with the smartphone, green gave significant treatment effects. It was believed that modern smartphone cameras are processing the pictures to appear 'beautiful' for landscapes and persons. This includes some adjustments of colour differences. Therefore, it is believed the results for a smartphone could be improved by accessing the raw data or circumventing this processing. able 3 - Effect of background soil N supply on delta yield and on delta colour using different colour sensors. The delta value is the ifference between measured values for nil N and 600N for each background level.

SR = "Simple ratio". Smartphone used only at harvest 2.

[00121] The delta values were plotted against fertiliser response, based on the average response to 50 and 100 kg N/ha. To test if a delta value taken at a time other than when the response occurred would also serve as a predictor of yield, the yield response at harvest 1 was also tested against the delta value for harvest 2.

[00122] The delta colour value using the Greenseeker from the first harvest explained 83% of the variation in N response (P<0.001, Figure 1) at the same harvest. The value of delta colour at times other than when the yield response was measured was also tested. The delta colour value for the second harvest (thus based on the residual effects of the 600N treatments) still explained 84% of the variation in yield response from the first harvest. No colour measurements were made at the third harvest.

[00123] The 'Simple Ratio' using the Tec-5 lens showed reasonable correlation with the N response, explaining 54-60% of the variation in N response (Figure 2).

[00124] The Smartphone was only trialled at the second harvest and so the delta colour values at this second harvest were compared with yield response (DM) at the first harvest showed a reasonable fit to the data (Figure 3). Using the red or green channels gave a reasonable fit to the response, explaining 50-70% of the variance (P<0.001).

[00125] For comparison, the delta yield values based on dry matter are also provided. Figure 4 shows the delta yield value based on the residual 600N yield taken at the second harvest was still a reasonable predictor of the previous yield response (r2=61%, P<0.001, Figure 4). When the delta yield value was calculated at the third harvest and compared with yield response at the first harvest it explained 78% of the variation in yield.

[00126] The experiment demonstrated that the use of sensing technology was a valid alternative to directly measuring yield in urine patch and non-urine patch areas.

REPRESENTAIVE FEATURES

1. A method for determining the responsiveness of an area of grazed forage to one or more nutrients , the method comprising the steps of a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral measurements from the at least one excrement patch and the at least one inter-excrement patch, and c) interpreting the difference in the spectral measurement from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

2. A pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients, the sensor comprising a detector for detecting spectral signals from at least one excrement patch and at least one inter-excrement patch, and a processor for quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch, wherein the processor interprets the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

3. A method of applying one or more nutrients to an area of grazed forage, the method comprising the steps of: a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch, c) interpreting the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients; and d) applying an amount of the one or more nutrients to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one excrement patch and the at least one inter-excrement patch, wherein the larger the difference the more of the one or more nutrients is applied.

4. The method or sensor of any one of the preceding clauses wherein the excrement is urine. 5. A method of applying nitrogen fertiliser to an area of grazed forage, the method comprising the steps of: a) obtaining at least one spectral measurement from at least one urine patch and at least one inter-urine patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch, c) interpreting the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch to determine the potential responsiveness of the area of grazed forage to nitrogen fertiliser; and d) applying an amount of the nitrogen fertiliser to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one urine patch and the at least one inter-urine patch, wherein the larger the difference the more nitrogen fertiliser is applied.

6. The method or sensor of any one of the preceding clauses wherein the difference in the spectral measurements from the at least one excrement patch and the at least one inter-excrement patch is interpreted by an algorithm to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

7. The method or sensor of any one of the preceding clauses wherein at least two spectral measurements are taken from the at least one excrement patch, or at least three spectral measurements, or at least four spectral measurements or at least five spectral measurements are taken from the at least one excrement/urine patch.

8. The method or sensor of any one of the preceding clauses wherein between 2 and 50 spectral measurements, or between 2 and 40 spectral measurements, or between 2 and 30 spectral measurements, or between 2 and 20 spectral measurements, or between 2 and 15 spectral measurements, or between 2 and 10 spectral measurements, or between 2 and 5 spectral measurements are taken from at least one excrement patch.

9. The method or sensor of any one of the preceding clauses wherein at least two spectral measurements are taken from more than one excrement patch, with each spectral measurement is taken from a different excrement/urine patch, or at least two spectral measurements are taken, or at least three spectral measurements are taken, or at least four spectral measurements are taken, or at least five spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch.

10. The method or sensor of any one of the preceding clauses wherein between 2 and 50 spectral measurements are taken, or between 2 and 40 spectral measurements are taken, or between 2 and 30 spectral measurements are taken, or between 2 and 20 spectral measurements are taken, or between 2 and 15 spectral measurements are taken, or between 2 and 10 spectral measurements are taken or between 2 and 5 spectral measurements are taken with the spectral measurements being taken from more than one excrement/urine patch.

11. The method or sensor of any one of the preceding clauses wherein at least two spectral measurements are taken, or at least three spectral measurements are taken, or at least four spectral measurements are taken, or at least five spectral measurements are taken from at least one inter-excrement patch.

12. The method or sensor of any one of the preceding clauses wherein at least two spectral measurements are taken, or at least three spectral measurements are taken, or at least four spectral measurements are taken, or at least five spectral measurements are taken, with the spectral measurements being taken from more than one excrement/urine patch.

13. The method or sensor of any one of the preceding clauses wherein between 2 and 50 spectral measurements are taken, or between 2 and 40 spectral measurements are taken, or between 2 and 30 spectral measurements are taken, or between 2 and 20 spectral measurements are taken, or between 2 and 15 spectral measurements are taken, or between 2 and 10 spectral measurements are taken, or between 2 and 5 spectral measurements are taken from more than one inter-excrement/urine patch.

14. The method or sensor of any one of the preceding clauses wherein where more than one spectral measurement is taken from the at least one excrement/urine patch the average of the spectral measurements is used to quantify the difference in the spectral measurements in step b) of the method.

15. The method or sensor of any one of the preceding clauses wherein where more than one spectral measurement is taken from the at least one inter-excrement/urine patch the average of the spectral measurements is used to quantify the difference in the spectral measurements in step b) of the method.

16. The method or sensor of any one of the preceding clauses wherein the excrement patch and the inter-excrement are predominantly on the same or similar soil type.

17. The method or sensor of any one of the preceding clauses wherein the forage is selected from any one or more of a grass, an herbaceous legume, crop residue, lucerne, forage brassicas, for example swede, turnip or kale, cereal crops, cover crops.

18. The method or sensor of any one of the preceding clauses wherein the excrement patch and the inter-excrement patch are predominantly the same forage type or are predominantly both the same genus of forage plant or are the same species of forage plant or are predominantly forage plants with the same number of chromosomes or are predominantly grasses or are predominantly grasses with the same number of chromosomes or are predominantly diploid grasses or are predominantly tetrapioid grasses.

19. The method or sensor of any one of the preceding clauses wherein substantially the whole area of grazed forage has been managed in substantially the same way.

20. The method or sensor of any one of the preceding clauses wherein the spectral measurement is measurement of light, preferably the spectral measurement is selected from one or more of measurement of red light, green light, infrared light.

21. The method or sensor of any one of the preceding clauses wherein the method further includes the step of obtaining at least one spectral measurement from a reference, preferably the difference in the spectral measurement from the at least one excrement patch, the at least one inter-excrement patch and the reference is interpreted to determine the yield potential of the area of grazed forage.

22. The method or sensor of any one of the preceding clauses wherein the spectral measurement is done with a camera or imaging device, preferably a digital multispectral camera or Active Light Source optical sensor, preferably a digital camera.

23. The method or sensor of any one of the preceding clauses wherein the spectral measurement is taken with a smart phone camera, satellite or aerial vehicle.

24. The method or sensor of any one of the preceding clauses wherein the spectral measurement from at least one excrement/urine patch and the at least one inter- excrement/urine patch are done within at least about 12 hours of each other, or within at least about 8 hours of each other, or within at least about 6 hours of each other, or within at least about 3 hours of each other, or within at least about 2 hours of each other, or within at least 1 hour of each other.

25. The method or sensor of any one of the preceding clauses wherein the spectral measurement of the at least one excrement/urine patch and the at least one inter- excrement/urine patch are obtained at the same time.

26. A device comprising a pasture sensor of clause 2.

27. The device of clause 26 wherein the device is a mobile phone, camera or imaging device.

28. Use of the pasture sensor according to clause 2, the device of clause 26 or the method of clause 1 to generate a prescription for the application of one or more chemicals to the area of grazed forage.

29. Use of clause 28, wherein the one or more chemicals is selected from one or more of a nitrogen source, potassium source, phosphate source, urease inhibitor, denitrification inhibitor, plant growth regulator, hormone, bio-stimulant, fertiliser and lime, preferably a nitrogen source, a phosphate source and potassium source, preferably a nitrogen source and potassium source, preferably a nitrogen source.

Claims

26 CLAIMS

2. The method of claim 1 wherein the excrement is urine.

3. The method of claim 1 or 2 wherein the difference in the spectral measurements from the at least one excrement patch and the at least one inter-excrement patch is interpreted by an algorithm to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.

4. The method of any one of the preceding claims wherein at least two spectral measurements are taken from the at least one excrement patch.

5. The method of any one of the preceding claims wherein at least two spectral measurements are taken from at least one inter-excrement patch.

6. The method of any one of the preceding claims wherein at least two spectral measurements are taken with the spectral measurements being taken from more than one excrement patch.

7. The method of any one of the preceding claims wherein where more than one spectral measurement is taken from the at least one excrement patch the average of the spectral measurements is used to quantify the difference in the spectral measurements in step b) of the method.

8. The method of any one of the preceding claims wherein where more than one spectral measurement is taken from the at least one inter-excrement patch the average of the spectral measurements is used to quantify the difference in the spectral measurements in step b) of the method.

9. The method of any one of the preceding claims wherein the excrement patch and the inter-excrement are predominantly on the same or similar soil type.

10. The method of any one of the preceding claims wherein the forage is selected from any one or more of a grass, an herbaceous legume, crop residue, lucerne, forage brassicas, for example swede, turnip or kale, cereal crops, cover crops.

11. The method of any one of the preceding claims wherein the excrement patch and the inter-excrement patch are predominantly the same forage type.

12. The method of any one of the preceding claims wherein substantially the whole area of grazed forage has been managed in substantially the same way.

13. The method of any one of the preceding claims wherein the spectral measurement is measurement of light.

14. The method of any one of the preceding claims wherein the spectral measurement is selected from one or more of measurement of red light, green light, infrared light.

15. The method of any one of the preceding claims wherein the method further includes the step of obtaining at least one spectral measurement from a reference.

16. The method of claim 15 wherein the difference in the spectral measurement from the at least one excrement patch, the at least one inter-excrement patch and the reference is interpreted to determine the responsiveness of an area of grazed forage to one or more nutrients.

17. The method of claim 15 wherein the reference is used to calibrate the spectral measurement(s) from the excrement and/or the inter-excrement patches.

18. The method of any one of the preceding claims wherein the spectral measurement is done with a camera or imaging device.

19. The method of any one of the preceding claims wherein the spectral measurement is taken with a smart phone camera, satellite or aerial vehicle.

20. The method of any one of the preceding claims wherein the spectral measurement from at least one excrement patch and the at least one inter-excrement patch are done within at least about 12 hours of each other.

21. The method of any one of the preceding claims wherein the spectral measurement of the at least one excrement patch and the at least one inter-excrement patch are obtained at the same time.

22. A method of applying one or more nutrients to an area of grazed forage, the method comprising the steps of: a) obtaining at least one spectral measurement from at least one excrement patch and at least one inter-excrement patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch, c) interpreting the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients; and d) applying an amount of the one or more nutrients to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one excrement patch and the at least one inter-excrement patch, wherein the larger the difference the more of the one or more nutrients is applied.

23. A method of applying nitrogen fertiliser to an area of grazed forage, the method comprising the steps of: a) obtaining at least one spectral measurement from at least one urine patch and at least one inter-urine patch within the area of grazed forage, b) quantifying the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch, c) interpreting the difference in the spectral signals from the at least one urine patch and the at least one inter-urine patch to determine the potential responsiveness of the area of grazed forage to nitrogen fertiliser; and d) applying an amount of the nitrogen fertiliser to the area of grazed forage based on the interpretation of the difference in the spectral signals difference from the at least one urine patch and the at least one inter-urine patch, wherein the larger the difference the more nitrogen fertiliser is applied.

24. Use of the method of claim 1 to generate a prescription for the application of one or more chemicals to the area of grazed forage.

25. The use of claim 24, wherein the one or more chemicals is selected from one or more of a nitrogen source, potassium source, phosphate source, urease inhibitor, denitrification inhibitor, plant growth regulator, hormone, bio-stimulant, fertiliser and lime, preferably a nitrogen source, a phosphate source and potassium source, preferably a nitrogen source and potassium source, preferably a nitrogen source.

26. A pasture sensor for determining the responsiveness of an area of grazed forage to one or more nutrients, the sensor comprising a detector for detecting spectral signals from at least one excrement patch and at least one inter-excrement patch, and a processor for quantifying the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch, 29 wherein the processor interprets the difference in the spectral signals from the at least one excrement patch and the at least one inter-excrement patch to determine the potential responsiveness of the area of grazed forage to the one or more nutrients.