Crop waste cattle feed solution ‘averts toxic fires’

ISLAMABAD: Researchers in India have found a way to enhance the nutritional value of crop residue so that it can be fed to cattle, deterring farmers from setting it on fire, a practice that destroys soil nutrients and causes severe environmental pollution.Farmers, particularly in northern Punjab and Haryana states, set rice and wheat stubble ablaze after harvesting, as a cheap way to clean up and fertilise fields before planting winter crops, according to a NASA report. But this results in a sharp deterioration in air quality in the capital of Delhi as well as the densely populated Indo-Gangetic Plain.

The new method, according to a study published December in Current Science, involves controlled spraying of urea onto straw residue during baling. After a curing period, the product showed enhanced palatability, digestibility and nutrient uptake, resulting in improved animal growth and milk production.
Urea is a naturally occurring chemical consisting of nitrogen, carbon, and oxygen, which has important uses as a fertiliser and as a feed supplement.

“Non-availability of labour, high cost of residue removal from the field and increasing use of combines in harvesting the crops are the main reasons for burning crop residues in the fields”

According to Satya Prakash Kumar, an author of the study and scientist at the Central Institute of Agricultural Engineering, in Bhopal, the effectiveness of the system depends on factors like the type of straw, urea concentration, moisture level, compaction, storage and environmental factors.

“A mechanised baler equipped with a urea spraying system was found to increase crude protein in wheat straw from 3.68 per cent to 10.10 per cent after treatment while energy was found to improve by three per cent compared to untreated straw,”

The urea spraying system, mounted on the mechanical baler, uses a series of flat nozzles to evenly discharge urea solution on the loose straw. Individual urea-treated bales of straw are tightly wrapped in polyethylene sheet, stacked and stored in shade at room temperature for a curing period of 21 days.
“Crop residue, being unpalatable and low in digestibility, cannot form the sole feed for livestock,” says Dilip Jat, co-author of the study. “Rice straw is a poor cattle feed due to high silica content and wheat straw is not preferred by animals as the stem is hard and difficult to chew.”