CN105684590A - Slope farmland nitrogen phosphor loss control method - Google Patents

Abstract

The invention discloses a slope farmland nitrogen phosphor loss control method comprising the following steps: A, charcoal trench design and construction: 1, building a charcoal trench: building the charcoal trench on the bottom of the slope farmland, wherein the trench side slope and bottom are respectively soil texture; 2, filling a soil-charcoal layer: filling soil and modified small aperture charcoal in the trench in layers according to a certain proportion; 3, planting a plant fence: planting the plant fence on the first original surface layer soil; B, building a water stop ridge: building the water stop ridge between the most bottom slope of the slope farmland and the edge of the charcoal trench; C, burying a diversion pipe: burying the diversion pipe on the bottom of the charcoal layer; D, charcoal trench management and maintenance: 1, regularly cleaning sands; 2, regularly inspecting and maintaining the water stop ridge. The slope farmland nitrogen phosphor loss control method is simple in operation, cannot content soil with crops, the charcoal can be repeatedly used, and the plant fence has high economic benefits, thus providing important meanings for controlling slope farmland and orchard surface source pollution.

Description

A method for preventing and controlling the loss of nitrogen and phosphorus in sloping cultivated land

technical field

The invention relates to the field of agricultural ecological environment protection, in particular to a method for preventing and controlling the loss of nitrogen and phosphorus in sloping cultivated land. The operation is simple, does not compete with crops for land, biochar can be reused, and hedgerows have high economic benefits.

Background technique

Sloping cultivated land refers to the dry land distributed on hillsides with poor ground flatness, prominent problems of running water, fertilizer and soil, and low crop yields. my country's sloping cultivated land is about 359 million mu, accounting for nearly 1/5 of the national cultivated land area. The loss of soil nutrients in sloping cultivated land is due to the rainfall acting on the surface soil, and the runoff causes the dissolution and loss of nutrients such as nitrogen and phosphorus in the soil, or the process that the granular nutrients contained and adsorbed in the runoff sediment migrate with the runoff and enter the water body.

Due to the inclination of sloping farmland, runoff that moves along the slope quickly appears on the surface after heavy rainfall, and nutrients necessary for crop growth such as nitrogen, phosphorus, and potassium in the soil flow out of the farmland with runoff and sediment loss. Studies have shown that the average losses of soil nitrogen and phosphorus in slope farmland in the Three Gorges reservoir area from May to August are 1.038kg·hm ^-2 and 0.509kg·hm ^-2 , respectively. The nitrogen and phosphorus elements in the soil are a double-edged sword. They are essential nutrients for plant growth stored in the farmland soil, and they are important pollutants for non-point source pollution of farmland when they are lost outside the farmland.

Studies have shown that the nitrogen and phosphorus nutrients in the surface runoff of sloping farmland are mainly nitrate nitrogen, ammonium nitrogen and inorganic phosphorus. Domestic sloping farmland nutrient loss prevention and control technologies mostly adopt agronomic measures such as no-tillage, hedgerows, optimized fertilization, and ridge farming on horizontal slopes; People build a three-dimensional agricultural system according to the slope change, and carry out multiple interception and control of slope agricultural non-point source pollutants. The application of these technologies has prevented or reduced the risk of non-point source pollution to a certain extent.

The adsorption of soil colloids to NH ₄ ⁺ mainly depends on electrostatic attraction. The balance of adsorption and desorption is affected by factors such as soil colloid type, clay content and soil pH value. The adsorption capacity of soil colloids to NH ₄ ⁺ is vermiculite>Montmorillonite>illite>kaolinite>sesquioxide; the adsorption mechanism of phosphorus (H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3- ) in soil is mainly obligate adsorption, and mainly occurs on iron , The surface of aluminum oxide, therefore, adding Fe(NO ₃ ) ₃ can greatly enhance its ability to adsorb phosphorus.

At present, the mechanism of biochar to reduce the loss of nitrogen in the soil mainly includes: (1) The small pore structure of biochar (less than 0.9nm) can reduce the seepage speed of soil nutrients, delay the dissolution and migration time of water-soluble ions, and strengthen the movement of water-soluble ions. (2) The rich oxygen-containing functional groups on its surface make biochar have high ion adsorption exchange capacity and certain adsorption capacity, which can adsorb dissolved NH ₄ ⁺ and NO ₃ in soil ^- plasma. If Fe(NO ₃ ) ₃ is added to the biochar, on the one hand, the surface of the biochar will be positively charged, which is conducive to the attachment of nitrifying bacteria and denitrifying bacteria on the surface; on the other hand, iron ions can accelerate the conversion of NH ₄ ⁺ -N to NO ₂ ^- -N transformation for short-range nitrification and denitrification. At the same time, denitrifying bacteria use biochar as a slow-release carbon source for denitrification, so that NO ₃ ^- is denitrified and denitrified into N ₂ and discharged into the atmosphere, reducing NO ₃ ^- in the soil from entering rivers due to leaching.

The main mechanisms for biochar to reduce phosphorus loss in soil are: (1) changing the availability of phosphorus through its anion exchange capacity or by affecting the activity/availability of cations interacting with phosphorus; (2) changing the microbial The soil environment provides indirect effects on phosphorus availability and uptake.

At present, most researchers apply biochar evenly to the soil, which can improve soil, increase fertilizer efficiency, and increase soil organic matter content. Soil surface plays little role in preventing and controlling the loss of nitrogen and phosphorus. Some people also bury biochar and soil under a certain proportion of agricultural non-point source polluted sewage collection ditches, but it is not practical on slope farmland with small plots, and no plants are planted to absorb the nitrogen and phosphorus accumulated in biochar. Make biochar non-reusable.

Contents of the invention

The purpose of the present invention is to propose a method for preventing and controlling the loss of nitrogen and phosphorus in sloping cultivated land. The hedgerow-soil-biochar-soil-biochar interception ditch passing through the bottom of the slope is used to intercept the loss of nitrogen and phosphorus in the runoff of slope farmland. When the runoff quickly flows to the bottom of the slope, it is blocked by a water retaining ridge to increase the runoff in biochar. -The retention time of the hedgerow interception ditch, through the repeated multiple filtration and adsorption of soil-biochar-soil-biochar and the repeated use of hedgerows, the nitrogen and phosphorus in the runoff can be intercepted to the greatest extent, which is very important for the prevention and control of sloping farmland and non-point source pollution of orchards are of great significance. The invention has simple operation, does not compete with crops for land, the biochar can be reused, and the hedgerow has high economic benefits.

A method for preventing and controlling the loss of nitrogen and phosphorus in sloping cultivated land, the steps of which are:

A. Build a biochar ditch: build a biochar ditch at the bottom of the sloping farmland, fill the ditch with biochar-soil-biochar-surface soil from bottom to top, and the ammonium nitrogen and phosphorus in the runoff can be absorbed by the soil and biochar Nitrate nitrogen is denitrified through denitrification, and the nitrogen and phosphorus in the runoff from the slopes are intercepted in the farmland or discharged into the atmosphere, and hedgerows are planted on the surface soil of the biochar ditch to achieve the goal of preventing The purpose of controlling the loss of nitrogen and phosphorus in slope farmland can also increase the economic income of farmers.

Biochar ditch design scheme, including:

a. The specifications of the biochar ditch are: 0.6~0.8m deep, 1.5m~2m wide, and the ditch length is consistent with the length of the farmland. The ditch is rectangular, the depth of the ditch is 2~3cm lower than that of the sloping land, and the material is soil.

b. Filling soil-biochar: Fill the ditch with biochar and soil with pores <0.9nm in layers, forming biochar-soil-biochar-surface soil from bottom to top, which will lead to nitrogen and phosphorus adsorption of eutrophication in water body On the surface of biochar it is either fixed in the soil or released into the atmosphere.

The thickness ratio of the soil to the biochar layer is 3:1 to 2:1, and the surface soil thickness is not less than 15 cm, which is conducive to the growth of hedgerows.

The biochar is added into the Fe(NO ₃ ) ₃ solution and soaked for 20-24 hours before being buried in the soil layer, and then dried at 75° C. for modification, and the concentration of the solution is 0.4-0.5 mol/L.

c. Plant hedgerows: cover the undisturbed surface soil above the biochar layer, plant hedgerows to intercept sediment and runoff, and at the same time, the roots of the hedgerows can absorb nitrogen and phosphorus adsorbed in the soil and biochar.

The hedgerow varieties are economic hedgerows such as perennial honeysuckle and day lily.

Honeysuckle planting: Select robust 1-2 year old branches without pests and diseases and cut them into 30-35cm, remove the lower leaves as cuttings. The row spacing is 0.9~1m, the hole spacing is 1m, and each hole has 5~6 cuttings, which are scattered and stand obliquely in the buried soil, with 15~20cm exposed on the ground, and the soil is compacted.

Day lily planting: transplant 1~2 year old day lily, row spacing 0.5~0.6m, hole spacing 0.2~0.3m, 2~3 plants per hole.

B. Build a water retaining ridge: Build a water retaining ridge between the lowest slope of the sloping farmland and the edge of the biochar ditch. The height is 15~20cm higher than the biochar ditch, whichever can block the downward runoff, and the material is soil.

C. Buried diversion pipe: Buried a diversion pipe at the bottom of the bottom biochar layer, the diameter of the diversion pipe is 8~11cm, the length is 0.8~1m, and the nozzle near the end of the biochar is wrapped with 400-mesh steel wire mesh, and the diversion pipe The length of the exposed ditch is 10-20cm, and one is buried every 3-5m, and the water filtered by biochar is discharged out of the field.

D. Management and maintenance of biochar ditch: regular maintenance of biochar ditch, including:

a. Regularly remove sediment: plant hedges and dams have the effect of intercepting sediment, and it is necessary to remove sediment every 30 to 40 days, keep the height of the biochar ditch 2~3cm lower than the slope farmland, and increase the runoff in the ditch retention time.

b. Regular inspection and maintenance of the water retaining sill: the water retaining sill is made of mud, and it should be checked every 30 to 40 days to see if the water retaining sill is washed away by runoff or leaks, and repaired in time.

Compared with the existing agricultural non-point source pollution prevention and control technology, the present invention has the following remarkable features and advantages:

(1) The hedgerow-soil-biochar-soil-biochar ditch can absorb and filter nitrogen and phosphorus in runoff from slope farmland and sediment more quickly and multiple times than biochar and soil mixed application;

(2) Not competing with crops for land, hedgerows can not only intercept and absorb nitrogen and phosphorus in runoff water, but also increase economic benefits;

(3) The triple interception of soil, biochar and hedgerow is better than a single technique;

(4) The operation process is very simple, avoiding the farmland hardening project, can be recycled for many years, has low management requirements and low cost.

detailed description

Example 1:

A method for preventing and controlling the loss of nitrogen and phosphorus in sloping cultivated land (taking a village in Xingshan County, Yichang City, Hubei Province as an example), the steps are:

A. Select a piece of sloping farmland in a village in Xingshan County, Yichang City, Hubei Province, and the main planting system is rape-corn.

a. Start construction after the corn is harvested. Build a biochar ditch with a width of 1.6m, a depth of 0.6m, and the same length as the farmland at the bottom of the slope farmland. The ditch body is rectangular, the depth of the ditch body is 3cm lower than that of the slope farmland, and the material is soil.

b. Filling the soil-biochar layer: Fill the soil and modified small-pore biochar evenly in the ditch to form biochar-soil-biochar-soil from bottom to top, wherein the thicknesses are respectively biochar (10cm)- Soil (20cm)-biochar (10cm)-soil (20cm), the first layer of soil is the original 20cm plow layer soil for planting hedgerows, biochar is fired from crop straw, the pores are less than 0.9nm, and the biochar is in 0.5 mol/LFe(NO ₃ ) ₃ solution for 24 hours and then dried at 75°C.

c, plant hedgerows: on the top of the filled biochar-soil-biochar-soil surface, choose strong and pest-free 2-year-old honeysuckle branches to cut into 30cm, and remove the lower leaves as cuttings. The row spacing is 1m, the hole spacing is 1m, and there are 5 cuttings in each hole. They are buried in the soil in a scattered shape, with 20cm exposed on the ground, and the soil is compacted.

B. Build a water retaining ridge: build a water retaining ridge between the lowest slope of the sloping farmland and the edge of the biochar ditch, the height of which is 20cm higher than the biochar ditch, and the material is soil.

C. Embedding diversion pipes: Embed diversion pipes with a diameter of 11cm at the bottom of the bottom biochar layer, bury one every 5m, and wrap 400-mesh steel wire mesh at the nozzle near the end of the biochar layer, and the diversion pipes are exposed to the length of the ditch The water filtered by biochar is discharged outside the field and samples are taken for analysis of total nitrogen and total phosphorus.

The above hedgerow-soil-biochar-soil-biochar interception ditch can reduce the surface runoff by 57%, reduce the output load of total nitrogen with runoff water by 84%, and reduce the output load of total phosphorus with runoff water by 91%. Increase income by 60 yuan.

Embodiment two:

A. Sloping farmland was selected in a village in Xingshan County, Yichang City, Hubei Province, and the main planting system was rape-corn.

a. Start construction after the corn is harvested. Build a biochar ditch with a width of 1.6m, a depth of 0.7m, and the same length as the farmland at the bottom of the slope farmland. The ditch body is rectangular, and the depth of the ditch body is 3cm lower than that of the slope farmland.

b. Filling the soil-biochar layer: Fill the soil and the modified small-pore biochar evenly in the ditch to form biochar-soil-biochar-soil from bottom to top, where the thickness is respectively biochar (10cm) - Soil (25cm) - Biochar (10cm) - Soil (25cm), the first layer of soil is the original 25cm plow layer soil for planting hedgerows, the biochar is fired from crop straw, the pores are less than 0.9nm, and the biochar is placed in the After soaking in 0.5mol/L Fe(NO ₃ ) ₃ solution for 24 hours, dry at 75°C.

c, plant hedgerows: on the top of the filled biochar-soil-biochar-soil surface, choose strong and pest-free 2-year-old honeysuckle branches to cut into 30cm, and remove the lower leaves as cuttings. The row spacing is 1m, the hole spacing is 1m, and there are 5 cuttings in each hole. They are buried in the soil in a scattered shape, with 20cm exposed on the ground, and the soil is compacted.

B. Build a water retaining ridge: build a water retaining ridge between the lowest slope of the sloping farmland and the edge of the biochar ditch, the height of which is 20cm higher than the biochar ditch, and the material is soil.

C. Embedding diversion pipes: Embed diversion pipes with a diameter of 11cm at the bottom of the bottom biochar layer, bury one every 5m, and wrap 400-mesh steel wire mesh at the nozzle near the end of the biochar layer, and the diversion pipes are exposed to the length of the ditch The water filtered by biochar is discharged outside the field and samples are taken for analysis of total nitrogen and total phosphorus.

The above hedgerow-soil-biochar-soil-biochar interception ditch can reduce the surface runoff by 48%, reduce the output load of total nitrogen with runoff water by 79%, reduce the output load of total phosphorus with runoff water by 84%, and each honeysuckle can Increased income of 64 yuan.

Claims (4)

1. the method hindering control sloping upland nitrogen and phosphorus loss, the steps include:

A, structure charcoal ditch: building a charcoal ditch at the bottom of sloping upland slope, in ditch, filling charcoal-soil-charcoal-topsoil from bottom to up；

A, charcoal ditch specification be that: 0.6 ~ 0.8m is deep, 1.5m ~ 2m width, ditch length is consistent with farmland length, and ditch body is rectangle, and the ditch body degree of depth is lower than sloping upland 2 ~ 3cm, and material is soil property；

B, filling soil-charcoal: the charcoal of hole < 0.9nm and soil layering are filled in ditch, form charcoal-soil-charcoal-topsoil from bottom to up, the nitrogen phosphorus causing body eutrophication is adsorbed on charcoal surface or is fixed in soil or is discharged in air；

C, planting plants hedge: above biological layer of charcoal, cover original state topsoil, planting plants hedge, Littoral Barrier and runoff；

B, building water-blocking bank: build a water-blocking bank between the minimum slope and charcoal furrow rim of sloping upland, highly higher than charcoal ditch 15 ~ 20cm, material is earth；

C, bury mozzle underground: bottom nethermost biological layer of charcoal, bury mozzle underground, draft-tube diameter is 8 ~ 11cm, length is 0.8 ~ 1m, the steel wire of 400 orders is wrapped up near charcoal one end mouth of pipe, it is 10 ~ 20cm that mozzle exposes the outer length of ditch, bury 1 underground every 3 ~ 5m, the water after charcoal filters is discharged outside field；

D, the administering and maintaining of charcoal ditch: charcoal ditch is wanted periodic maintenance, including:

A, regularly remove silt: silt is had interception result by plant hedge and water-blocking bank, needs within 30 ~ 40 days, remove a silt, keeps the height of charcoal ditch lower than sloping upland 2 ~ 3cm, increases runoff retention time in ditch；

B, the making regular check on and safeguarding of water-blocking bank: water-blocking bank is shale, answer 30 ~ 40 days and check that whether water-blocking bank is washed away side slope by runoff or leak, repair in time。

2. a kind of method hindering control sloping upland nitrogen and phosphorus loss as claimed in claim 1, is characterized by:

The thickness of described soil and biological layer of charcoal ratio is for 3:1 ~ 2:1, and topsoil thickness is not less than 15cm, is beneficial to plant hedge growth。

3. a kind of method hindering control sloping upland nitrogen and phosphorus loss as claimed in claim 1, is characterized by: described charcoal adds Fe (NO before embedment soil layer₃)₃After soaking 20-24 hour in solution, drying and be modified at 75 DEG C, the concentration of solution is 0.4-0.5mol/L。

4. a kind of method hindering control sloping upland nitrogen and phosphorus loss as claimed in claim 1, is characterized by:

Described plant hedge kind is the economic living hedges such as perennial Flos Lonicerae, Radix hemerocalis plicatae；

Flos Lonicerae is planted: selects 1～2 year raw branch to be cut into 30～35cm, plucks bottom leaf and do cutting；Line-spacing 0.9 ~ 1m, cave is from 1m, and every cave 5～6 root cutting, dispersion shape is tiltedly stood and buried in soil, exposes 15～20cm, fill compaction on the ground；

Radix hemerocalis plicatae plant: transplant 1 ~ 2 age Radix hemerocalis plicatae, line-spacing 0.5 ~ 0.6m, cave from 0.2 ~ 0.3m, every cave 2 ~ 3 strain。