Current Nutrient Management Strategies on Minnesota's Outwash Sands

摘要

Extensive studies on nutrient management practices have been conducted since 1992 with the three dominant but distinctly different types of agricultural cropping systems which coexist on Minnesota's outwash sand plains. This study focused on : 1) irrigators primarily dependent on corn production and most were dairy operations; 2) non-irrigators dominantly dairy; and 3) irrigated potato producers. Nutrient inputs, yield and yield goals, and a variety of N management strategies were collected on a filed-by-field basis covering 67,000 cropland acres involving 119 farms. Commercial fertilizer rates on cron for both irrigated and dryland production were in excellent agreement with Universitty of MN(UM) recommendations. However, the cresiting process was seriously confounded by the addition of manure. Virtually no manure credits were accounted for resulting in over-applications of 60-70 Ib N a-1 across all manured corn acres. On the irrigated farms, 30% of the corn acres were manured yet contributted 90% of the N in excess of UM recommendations. Accepttance of manure crediting on the outwash sands significanttly lage behind other livestock regions of the state. Timing and source selection of N fertilizers associated with potato production were also in excellent agreement with UM recommendations. The concept of multiple N applications was widely accepted; the average potato field received 4 N applications per season. Over 50% of the growers were using petiole analysis for making real time N management decisions. Unlike tthe other two groups, existence of manure and legume credits was uncommon in this cropping sequence which greatly simplified N management. Across all potato acreage, N inputs averaged 34 Ib a-1 higher than UM recommendations. Potato producers could also make significant environmental advances by reducing starter N by 35%.