Improving soil nutrition with poultry litter application in low-input forage systems
Despite high volumes of manure production in the Shenandoah Valley of Virginia, there are still areas of forage production that are nutrient deficient because manures have traditionally been applied to higher-value row crops. This study was conducted to compare the effects of poultry litter and inorganic fertilizers on soil fertility and forage production. Two sites had the same treatments applied for two consecutive years: (1) split application of litter (half in spring and half in summer); (2) inorganic fertilizer at the same N, P, and K rates as Treatment 1; (3) single spring application of litter; (4) inorganic fertilizer at the same N, P, and K rates as Treatment 3; and (5) unfertilized control. Forage yield, soil pH, Mehlich 1 phosphorus (M1P), P uptake, and water-soluble phosphorus (WSP) were measured during this experiment. On average, soil pH was 0.2 higher for litter than inorganic fertilizer treatments, but this difference wasn't significant. The M1P and WSP both increased throughout the 2 yr, but no significant differences were found among split and single application or litter and inorganic fertilizers. Fertilization increased yield 3.5 Mg ha–1 on average, and application timing and fertilizer types produced similar yields. The P balance revealed that, when using N-based applications, neither site removed adequate P from forage yield to prevent environmental concerns. Our data showed that poultry litter was comparable with inorganic fertilizer in terms of increasing soil WSP, M1P, and forage yield, and the timing of application made no difference.