Submitted to: Manitoba North Dakota Zero Till Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/24/2005
Publication Date: 2/1/2005
Citation: Merrill, S.D., Tanaka, D.L., Krupinsky, J.M., Liebig, M.A., Hanson, J.D., Hendrickson, J.R., Ries, R.E., 2005. Pg. 48-53. Crop sequencing: making soil biology and water use improve system efficiency. Manitoba North Dakota Zero Till Conference Proceedings. Interpretive Summary: Soil-crop production systems that incorporate a diversity of species abate pest scourges of weeds, insects, and plant disease through annual to multi-year scales of soil health improvement. Through the experimental agronomic system of crop sequence experiments, where all possible interactions among a list of crops is observed with two-year crop matrices, we have observed certain interactions that appear to be characteristic. Legume crops (dry pea, dry bean, and soybean) enhanced the yields of other crops in general, results believed to be above and beyond any nitrogen fixation effect because all crops, including legumes, were given adequate fertilizer N. Mustard family crops canola and crambe tended to have negative effects on other crops, which is possibly attributable to the fact that these crops are non-endomycorrhizal. Sunflower uses more water than any of the other crops, and there are many reports by farmers and researchers of sunflower lowering the yields of subsequent crops under critically limited water situations. However, in this study, precipitation was well-distributed and either average or well above average, and sunflower exerted relatively strong positive crop sequential effects on other crops. Cropping system efficiency is gained by using sequences that combine favorable soil biology while maximizing water use to the extent that crop water stress is not significantly increased
Technical Abstract: A crop sequence experiment under no-tillage that examined all 100 possible two-year combinations of ten crops (barley, dry bean, dry pea, canola, crambe, flax, safflower, soybean, spring wheat, and sunflower) using a checkerboard arrangement of 9-m square plots was carried out twice using 4-fold replication. The crop matrix was followed with a year of spring wheat. Legume crops produced significant enhancive effects on seed yield of other crops, while mustard family crops (canola, crambe), which are non-endomycorrhizal, had significant detrimental effects on seed yield of some other crops. Crops growing on their own residue had moderately detrimental effects. The project was carried out in years of normal to well above average precipitation, and water use by sunflower, which was greater than all the other crops, did not case any apparent yield decrement to other crops. Instead, sunflower had the greatest yield enhancive effects on other crops. Heavy water use by both sunflower and safflower is interpreted as being the reason these oilseed crops had a significantly positive impact on spring wheat yield compared to continuous (3-year) wheat. Cropping system efficiency is gained by using sequences that combine favorable soil biology while maximizing water use to the extent that crop water stress is not significantly increased.