Crop rotation, residue durability, and nitrogen fertilizer effects on winter wheat production

Alternative rotation crops and residue surface cover are needed for sustainable cropping systems. In two large-scale field trials near Genesee, ID,'Gisilba' condiment mustard (Sinapis alba L), 'Columbia' dry pea (Pisum sativum L.), and 'Crimson' lentil (Lens culinaris Medik.) spring crops were evaluated for their agronomic effect on subsequent 'Madsen' winter wheat (Triticum aestivum L.) during 1994-1995 and 1995-1996. After harvesting the spring crops, a chisel (applying 55 Ib N/acre, 30 Ib P/acre, and 20 Ib S/acre) and two passes with a field cultivator with a harrow attachment prepared the seedbed for planting with winter wheat. Crop residue level and retention was measured over winter as the wheat crop became established. In the spring of each second year, incremental levels of N fertilizer (from 0 to 200 Ib/acre) were applied to the winter wheat on a small plot section of each large plot using a split-plot arrangement. Residues from the three spring crops showed very little winter decomposition. Mustard residues maintained a surface cover above 50%, greater than the 30% for per and 25% for lentil. Winter wheat yields were 109 bu/acre following pea, 109 bu/acre following lentil, sind 102 bu/acre after mustard in 1994-1995, but no significant differences were found in 1995-1996. Winter wheat test weight was statistically higher following lentil, but no differences in grain protein content or seed weight were observed. There were no significant differences in residual soil inorganic N among the spring crops and N fertilizer response regression equations of the subsequent winter wheat were not significantly different among previous crops. This information shows mustard, pea, and lentil can be beneficial rotational crops prior to winter wheat. Mustard is superior in residue production and could be a valuable alternative crop to pea and lentil in sustainable cropping systems that optimize crop production while reducing problems of soil loss.