Soil management effects on planting and emergence of no-till corn

Information is lacking on the influence of soil conditions on planting and emergence of row crops. We studied no-till planting and emergence of corn (Zea mays L.) as influenced by nine previous management practices, ranging from 6-yr bromegrass (Bromus inermis Leyss.), B-6, to 6-yr conventional-till corn, C-6, on a silt loam. Soil structure (air entry value, bulk density, dispersible clay, mass fractal dimension, tension draining the smallest pores, wet-aggregate stability) and water content measurements were made prior to planting. An instrumented 97 kW Case-IH Magnum tractor and a modified John Deere model 7000 planter were used for corn planting. Tractor performance and planter draft were measured with transducers and a data logger Fuel consumption (r = 0.92), ground speed (r = -0.79), and wheel slip (r = 0.75) were linearly related to draft. Corn seedling emergence was measured 14, 18, and 22 days after planting (DAP). The effect of management was significant for two-thirds of the structure measurements, all of the equipment variables, and corn emergence 14 DAP. Planter draft ranged from 12 kN in C-6 to 15 kN in B-6. Wet-aggregate stability was the only structure measurement correlated with draft (r = 0.33), fuel consumption (r = 0.34), speed (r = -0.30) or slippage (r = 0.29). These relations were explained by the fact that wet-aggregate stability and draft both increase with increasing root length density. Corn emergence was more rapid in B-6 than in C-6, but did not correlate with any of the structure measurements. Further research is needed to determine if this result was due to improved soil structure or shallower seed placement following forages.