Farm Yard Manure (FYM): Preparation and Use

After reading this article you will learn about the preparation and use of Farm Yard Manure (FYM).

Preparation of Farmyard Manure:

(i) In India, a major portion of cattle dung is used as fuel by farmers, after being converted into dung cake. Urine is completely soaked into the earthen floor of the cattle shed, thus wasting a major portion of the cattle dung and urine.

(ii) The mixture of cattle dung and urine soaked litter is usually left exposed to hot sun and heavy rain when urea of urine and dung is rapidly decomposed to ammonia and is lost as shown in the equation.

Cattle dung is rapidly decomposed by high temperatures, when the complex organic form of nutrients contained in them are converted to simple inorganic forms of nutrients which are washed down by high rainfall.

How to Reduce Loss of Nutrients from Cattle Dung and Urine?

(i) By using a better method of collection of dung and urine:

Farmers should be provided with other sources of cheap fuel. A Biogas plant should be provided to them at a subsidized rate. The floor of the cattle shed should be cemented to prevent from soaking in the urine. Sufficient quantity of waste organic material should be used for soaking the urine.

(ii) By the use of chemical preservatives:

Urea of urine and dung is decomposed by the urease enzyme to ammonium carbonate, which is very unstable and decomposes to ammonium carbonate, carbon dioxide and water. So gypsum or single super phosphate should be spread evenly over the litter.

These chemical preservatives reduce the loss of ammonia by converting ammonium carbonate to ammonium sulphate as shown in the following equations. If gypsum is used, ammonium sulphate and calcium carbonate are formed.

When manure + heap dries up, the ammonium sulphate reacts with calcium carbonates to re-form ammonium carbonates, which are then decomposed to ammonia, carbon dioxide and water.

If a single super phosphate is used, then ammonium sulphate and insoluble tricalcium phosphate are formed, as shown in the following equation:

Thus single superphosphate is better than gypsum because tricalcium phosphate does not react with ammonium sulphate and there is no loss of ammonia.

(iii) A better method of preparation of farm yard manure (FYM):

The manure pit should be about 0.9 metres deep, 1.8 to 2.4 metres wide and of any suitable length. The length of the manure pit should be about 5 meters if the farmer has 2 pairs of animals. The manure pit should be provided with a roof to protect the FYM from the hot sun and heavy rain. The mixture of cattle dung and urine soaked litter should be directly taken to the manure pit and evenly spread uniformly at its bottom.

If necessary, water should be uniformly added to it. The daily collection of the mixture of cattle dung and urine soaked litter is spread evenly over the previous layer. This is continuing till the manure heap rises about 30cms above the ground. It is then watered thoroughly and mud plastered.

The farm yard manure is ready in about six months. In India, Farm Yard Manure contains (Percentages on dry matter) about 0.32 per cent nitrogen, 0.05 per cent phosphorus (P), 0.25 per cent potassium (K), 1.20 per cent calcium (Ca) and 0.33 per cent magnesium (Mg).

Use of Farm Yard Manure:

Partially rotten farm yard manure should generally be applied 3 to 4 weeks before sowing the crops. This farm yard manure FYM will decompose in moist soil to improve the soil structure and release the nutrients contained in it, in the soluble form for growth of the crop.

If it is applied too long before sowing the crop, the nutrients are lost by leaching by rain water. Well-rotted farm yard manure should be thoroughly worked into the soil just before the crop is sown.

The application of Farm Yard Manure and fertilizers to young vegetable and fruit plants have given the best results. As farm yard manure contains a relatively low amount of phosphorus, it should be used in conjunction with single super phosphate (Bone meal to acid soils) as a basal dose and nitrogenous fertilizers should be used as a top dressing.