Organic fertilizer effects on growth, crop yield, and soil microbial biomass indices in sole and intercropped peas and oats under organic farming conditions.


01. C-rich manure and compost improved the yield of peas but not that of oats.

02. Intercropping decreased pea yield, but pea/oat intercropping displayed a yield advantage over sole cropping.

03. Organic fertilization stimulated microbial biomass and activity, but not intercropping.

04. Horse manure was more readily available to soil microorganisms than compost.

05. Positive residual effects of organic fertilizers were observed on the succeeding  wheat.

Balanced nutrition is the base for a healthy plant. Amongst the different constituents such as silica, phosphate, potash and nitrogen, phosphate is one of the significant nutrients. Phosphate forms a major part of nucleic acids and is an energy source for the plant. Root growth, yield and absorption of potassium, manganese and nitrogen in balanced form depend on proper absorption of phosphorus.

Depending on the pH of the soil, the water soluble part of the conventional chemical phosphatic fertilizers gets converted into an insoluble form soon after it comes in contact with substances like iron, aluminum, calcium, or magnesium salts in the soil.

The process is known as Phosphate Fixation. Fixed phosphate, which cannot be utilized, creates phosphate banks in the soil. These banks will remain unutilized for years together resulting in non-fertile land. As a result, typically about 70-90% of the phosphorus gets fixed and only 10-30% can be utilized by the plant. Organic Fertilizer helps overcome the phosphate fixation problem. The base of organic fertilizers is typically humus, which is compost manure. Some herbal extracts and mineral phosphate are added to it as nutrients for microbes and the plants. The Organic Fertilizer provides phosphorous to the plant over an extended period in smaller doses as necessary for healthy growth. The humus, presence of organic carbon and lower pH create favorable conditions to avoid the phosphate fixation process.

Eventually 90-95% of the total phosphorus can be utilized by the plant for its nutrition. The humus makes the soil porous and rich in microbes. It is also observed that continuous use of Organic Fertilizer can make available over time the previously fixed phosphate. On application of Organic Fertilizers, considerable improvement in yield even up to 25%, have been recorded.

Recent developments in the technology have opened the possibility of using food grain and vegetable waste other than dung for biogas generation. Even the waste cake that is left after extracting oil from seeds can be used to generate biogas. Interestingly, the gas output of this starch or protein based feedstock is multi-folds than that of the cow dung.