Crop residue is not a waste. It is a precious commodity and essential to preserving soil quality.Rattan Lal, SSSA President, has a timely message to his fellow Society members in the May issue of CSA News (regretfully subscription only). It is that we must take this opportunity to break the cycle of soil destruction that characterizes the rise and fall of civilized man. Biofuels adds unprecedented value to biomass production. Rattan Lal sketches out the numbers, comparing potential demand to crop residue available. With demand tracking above supply, the temptation is to mine the soil of its vitality. Rattan Lal observes that soil exploitation is the primary contributing factor to desertification.
Production systems must be developed so that ethanol produced must be at least C neutral if not C negative. Temptations [to mine soil vitality] aside, biofuels produced from crop residues may neither be free nor cheap.
Harvesting crop residues for use as fodder for livestock, residential fuel for cooking and heating, construction material, and other competing uses is a reality in sub-Saharan Africa, South Asia, China, and other developing countries. Therefore, it is not surprising that these are also the regions that have been plagued with severe problems of soil degradation.Rattan Lal has done an admirable job in this appeal to the his fellow SSSA members. He has included constructive comment on tools and processes available to make biofuels production compatible with maintaining soil vitality. But the undercurrent message is that those of us who love soil must involve ourselves in the process, the policy, and the public discussion of our transition to sustainable energy.
With a severe decline in physical quality, degraded soils do not respond to fertilizers even if made available at a subsidized price. Adverse effects of none or low rates of applications of fertilizers and other amendments on agronomic production and soil quality have been exacerbated by the perpetual and indiscriminate removal of crop residues coupled with uncontrolled and excessive communal grazing.
The stubborn trends of low crop yields and perpetual hunger and malnutrition in sub-Saharan Africa and in regions of rainfed agriculture in South Asia cannot be reversed without returning crop residues to the soil and also supplementing them with liberal applications of other biosolids.
Leave comment or email me if you would like to request a copy of Rattan Lal's May address. Or better yet, join SSSA.