CS272804B1 - Leaching solution for potassium, magnesium, calcium, sodium. manganese and to plants accessible phosphorus determination in soil - Google Patents

Abstract

The leaching solution for determination of potassium, magnesium, calcium, sodium, manganese and phosphor, which is available to plants in the soil, contains 0.5 mole of ammonium acetate, from 0.01 to 0.02 mole of ammonium fluoride, possibly acetic acid or ammonia up to pH 7, and the rest is water per 1 l. After having displaced ammonium sorbed in the soil by the solution of potassium chloride, it is possible to carry on with determination of the cationic exchange capacity of the soil.

Description

The invention solves an economical leach solution and extraction procedure for determining the stock of basic, plant nutrients potassium, magnesium, calcium, sodium, manganese and phosphorus in the soil, as well as determining the cation exchange capacity.

The closest solution to our solution is the world-wide Mehlioh (II) method, where from one leachate, which is a mixture of acetic acid, ammonium chloride, ammonium fluoride and hydrochloric acid, it is possible to determine the supply of soil with phosphorus, potassium, calcium, magnesium and manganese. However, it is not possible to determine the cation exchange capacity for which it is necessary to prepare a new leachate from a new soil sample.

A new leach solution of 0.5 M to 1 M ammonium acetate and 0.01 to 0.02 M ammonium fluoride at pH 7 is proposed. This leach solution, due to its excess of ammonium ions, displaces all exchange cations from the soil and replaces them they absorb ammonium ions. Since the leachate also contains ammonium fluoride, the content of plant-accessible phosphorus is successfully determined. In another operation, after the sorbed ammonium ions have been washed out of the soil and determined, the cation exchange capacity is obtained after the calculation.

The advantage of said leach solution and of the soil extraction process is that from a single portion of the sample the set of exchange cations, the content of plant-accessible phosphorus and the value of cation exchange capacity are determined. There is therefore a labor saving, because the old methods must weigh 2 to 3 times. Furthermore, at a reduced concentration of the leaching solution compared to other methods, chemicals are saved. Furthermore, this method is less time consuming.

The proposed leach solution and soil extraction procedure were tested on a set of 18 soil samples. considerably different chemistry from the whole Czechoslovakia. The results of the assay, as compared to the standard method for determining cation exchange capacity (KVK) and exchange cations (Technical Bulletin 27: The analysis of agricultural materials. Ministry of Agriculture, Fisheries and Food, London 1973), are as follows:

Soil characteristics Tightness of the relationship, expressed in correlation coefficient

K7K 0.9936

Ca 0.9255

Mg 0.9850

K 0.9937

The great advantages of the leach solution are in the improved characteristics of the nutrient elements in the soil. By using a neutral solution containing ammonium fluoride, the content of plant-accessible phosphorus is better determined because it does not dissolve (like most methods used to date using acidic leaching solutions) to plants of poorly accessible apathetic forms of phosphorus in the soil. aluminum-bound phosphorus, which is accessible to plants in the slightly acidic to neutral soil pH range. The suitability of this leach solution and the procedure for the determination of plant-accessible phosphorus is evidenced by the high tightness of the relationship between the measured values and the phosphorus content of the plants compared to other methods used. The following results were obtained:

Method of determining acceptable P (18 soils) Correlation coefficient with P content in the plant Egner 0.4887 Olsen 0.5594 Mehlich II 0.5072 Sorption Index (Baoh, Williams) -0.5413 Intensity Factor (0.01 M CaClg) 0.6231

ff

CS 272 804

Method of determining acceptable P ___________

EUP, fraction 3), 6), 0)

New method (leach solution) Product (New method x KVK)

Correlation coefficient _____s_content _- P_vjjostlinš -______

a) 0.3138 b) 0.5343, o) 0.4790 0.6346 0.7685

Determination of the cation exchange and cation exchange capacity allows for a better characterization of the K and Mg allogenity in the soil and also allows for the determination of liming needs. The parallel identification of KVK can also be used to better assess the phosphorus enrichment of soil, as demonstrated by comparative test results. The proposed leaching solution thus better characterizes the nutrient supply of the soil, thus allowing better fertilizer dosing and economical use.

Example of leach solution composition and soil extraction procedure (method description)

Weigh 5 g of air-dried soil sieved through a 0,5 mm sieve into a 150 ml beaker. Place 100 roles of a 0.5 M ammonium acetate solution, which still contains 0.015 M ammonium fluoride and has a pH of 7.0 (this pH is achieved by treating the cells with acetic acid or ammonia). Stir immediately and do not bend to stand overnight. The next day, mix the contents of the beaker 4 times at 10 minute intervals. The last mixing is done directly before converting to the filter. After filtration, the filtrate obtained is used for the determination of exchange cations (by the usual method, for example, AAS) and for the determination of the plant-accessible phosphorus content (colorimetrically as phosphomolybdenum blue). Quantitative conversion of the soil from the beaker to the filter with ethanol is then carried out. To remove the unsorbed free NH4 + ions, the soil is further eluted with ethanol, four increments of 25 ml in succession, until the previous ethanol batch is completely filtered off. The eluted soil is then eluted successively into a 100 ml volumetric flask with 25 ml of 10% KCl, the pH of which is adjusted.

2.5 with hydrochloric acid. The procedure is the same as for ethanol washing. Wash until 100 ml graduated. The volumetric flasks are then made up to the mark with a KOI solution, mixed, and this extract is used to determine the ammonium ions from which the cation exchange capacity value is calculated.

The invention can be used in agricultural research and in practice as part of agrochemical testing and the like.

Claims (1)

Leach solution for the determination of potassium, magnesium, calcium, sodium, manganese and phosphorus available in the soil, characterized in that it contains by weight per liter 0,5 mol to 1 mol of ammonium acetate, 0,01 mol to 0,02 ammonium fluoride or acetic acid, nobo ammonia, to pH 7 and water as the remainder.