Quantifying straw removal through baling and measuring the long-term impact on soil quality and wheat production
Crop residues are considered the feedstock of choice for the production of ethanol, but removing crop residues may negatively impact soil productivity. The objectives were to quantify the proportion of total aboveground crop residues removed through baling and to evaluate the effects of 50 yr of straw removal with baling on soil quality and wheat (Triticum aestivum L.) production. The first study evaluated three harvesting systems and their impact on straw removal with baling. The second study measured straw removal after 50 yr on soil quality and wheat production using a fallow-spring wheat-spring wheat rotation (F-W-W) with three different treatments imposed. One treatment was not fertilized with straw retained, and the other two were fertilized with N and P but one treatment retained the straw while the other had the straw baled every year during the cropping years. The proportion of total aboveground residues other than grain removed with baling ranged from 22 to 35% or 26 to 40% depending on the method of calculation based on the first study. Measurements of soil organic carbon (SOC) and nitrogen (SON) showed no differences after 50 yr of straw removal, and spring wheat grain yields and grain protein concentration were also not affected based on the second study. The potential therefore exists to use crop residues for ethanol production or other industrial purposes without adversely affecting the long-term productivity of medium- to heavy-textured soils providing that <40% of the total aboveground residues other than grain are removed and the frequency of removal is no more than 2 yr out of three.