Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/1997
Publication Date: N/A
Interpretive Summary: Maintaining crop residues on the soil surface is very important for adequate erosion control on sloping land in the Pacific Northwest. Most of the rainfall comes in the winter when crop growth is minimal and soils often partially frozen. No-till cropping leaves crop residue, but frequently lowers yield when wheat follows another cereal crop. Farmers are very reluctant to adopt any conservation practice that may lower yield and reduce profit. We designed a 5-year study to determine the impact of standing wheat residue (stubble) on yield of winter wheat and spring wheat in no-till systems, and find out if manipulation of fertilizer practices affected yield performance. Flailing or burning of residue increased the yield of winter wheat by 15%, but had little effect on spring wheat yield. Poor light quality and lower soil temperature in standing residue appeared responsible for reduced yield. Fertilizer increased crop yield but did not alleviate the detrimental effect of standing residue. Since burning of residue predisposes sloping soils to erosion, manipulation of straw on the soil surface prior to seeding appears necessary to provide a better environment for developing seedlings in conservation tillage systems.
Technical Abstract: Cereal residues are the primary method of erosion control in semi-arid regions of the Pacific Northwest, but surface residues can reduce yield when a cereal follows a cereal. Reduced yield slows adoption of conservation practices such as minimum- or no-tillage. We conducted a 5-year study to determine if standing wheat residue affected yield of the following wheat crop when grown no-till, and if any adverse effects could be overcome with increased fertilization. Nitrogen application rates ranged from 0 to 168 kg ha-1, and included phosphorus and sulfur. Fertilizer was banded 5 cm blow the seed to minimize nutrient immobilization by residue. Flailing or burning of residue increased winter wheat yield 15%, but did not affect spring wheat yield. Poor light quality and lower soil temperature in standing residue appeared responsible for reduced yield. Fertilizer application increased crop yield substantially, but did not overcome the adverse effect of standing residue. Since burning predisposes sloping soils to erosion, manipulation of straw on the soil surface prior to seeding appears necessary to maintain yield in conservation tillage systems.