Evaluation of pre-plant incorporated manure and phosphorus fertilizers on alfalfa yield, nutritive value, and residual soil characteristics

Abstract

Managing adequate levels of plant available P in soil is an important management practice for boosting alfalfa (Medicago sativa L.) yields and nutritive value. Although several ways of supplementing P at various stages of plant growth are in practice, pre-plant application of P through various organic and inorganic nutrient sources are largely under-investigated. Therefore, a three-year study was conducted at the New Mexico State University Rex. E. Kirksey Agricultural Science Center, Tucumcari, NM USA, to investigate the impact of manure (pre-plant applied @ 22.5 Mg ha−1vs. no manure) and inorganic P sources (00-46-00 or 11-52-00) applied to soil either in one-time bulk (336 kg P2O5 ha−1 preplant incorporated) or split applications (112 kg P2O5 ha−1 preplant incorporated with an additional 112 kg P2O5 ha−1 surface-applied annually) on the yield and nutritive value of alfalfa and residual soil characteristics. Results demonstrated that pre-plant manure application had statistically no advantage in improving the alfalfa forage yield compared to control (p > 0.05), although there was strong evidence of a consistent yield increase trend in all manure treatments. Forage nutritive value parameters such as ADF (Acid Detergent Fiber), NDF (Neutral Detergent Fiber), K, and Zn were significantly improved by manure supplementation. Manure application improved most soil quality parameters, especially the soil Nitrate-N, Olsen P, K, S, and Zn contents. Inorganic P fertilizer type or application strategy had no significant impact on alfalfa yield and nutritive value and soil characteristics. Most interactions (both two-way and three-way) among the tested treatments had no significant impact on the study parameters.