Crop/Forage/Soil Management/Grassland Utilization

For the long-term sustainability of the dairy industry in the Northeastern USA, manure nutrient application rates should not exceed crop nutrient removal once aboveoptimum soil fertility levels are reached. Dairy producers have shown a growing interest in brown midrib (BMR) forage sorghum (Sorghum bicolor (L.) Moench.) · sudangrass (Sorghum sudanense Piper) hybrids (S · S) as a more environmentally sound alternative to maize (Zea mays L.) but data on S · S nutrient removal rates are scant. Our objectives were to determine N, P, K, Ca and Mg removal with harvest as impacted by N application rate, using six N rate studies in New York. One of the six sites had a recent manure history. Although site-to-site differences existed, N application tended to decrease P and K and increase N, Ca and Mg concentrations in BMR S · S forage. Nutrient removal and yield were highly correlated for all sites except one location that showed a K deficiency. The crop removed large amounts of P and K in the manured site, suggesting that BMR S · S is an excellent scavenger of these nutrients. If manure is applied mid-season, forage K levels are likely too high for feeding to non-lactating cows.