No-tillage alone not enough against water pollution
(9 months ago)
Washington D.C. [USA], Sep 24 : A team of researchers has found that the adoption of no-till - a way of growing crops or pasture from year to year without disturbing the soil through tillage - may increase water pollution from nitrate via leaching.
Researchers from the Indiana University - Purdue University Indianapolis suggested that no-till needs to be complemented with other techniques, such as cover cropping and inter-cropping or rotation with perennial crops, to improve nitrate retention and water-quality benefits.
The team conducted a meta-analysis to compare runoff - the draining away of water - and leaching - drain away from soil - of nitrate from no-till and conventional tillage agriculture- cultivation of the soil using plow, harrow and other farm tools or mechanical implements to prepare the field for crop production.
Surface runoff and leaching are two major transportation pathways for nitrate to reach and pollute water.
Due to its mobility and water solubility, nitrate has long been recognised as a widespread water pollutant.
"What we found is that no-till is not sufficient to improve water quality," said corresponding author Lixin Wang.
"In fact, we found that no-till increased nitrogen leaching," Wang added, saying that the adoption of no-till resulted in increased nitrate loss via leaching due to the frequent occurrence of macropores, such as those created by dead roots and earthworm burrows, in soils that have been under long-range no-tillage management.
No-till leaves crop residue on the soil surface and limits soil disturbance except for small slits to add fertilizer.
It reduces soil erosion by avoiding tilling year after year, which leads to soil getting washed away into lakes and rivers. Because reducing soil loss reduces nutrient loss, it was assumed that no-till would reduce water pollution, Wang noted.