Compost Organic Amendments in Fodder Crops: Effects on Yield, Nitrogen Utilization and Soil Characteristics

Abstract

AbstractAgronomic value and environmental impact of two composts were evaluated in a three-year field experiment (2002, 2003 and 2004) on alfalfa and cocksfoot in Southern Italy. The effects of Municipal Solid Waste compost (MSW), Olive Pomace Compost (OPC), mineral fertilizer (Min) (phosphorus as 75 kg ha−1 for alfalfa and nitrogen as 50 kg ha−1 for cocksfoot) and an unfertilized treatment (Contr) were compared on crop yield, soil characteristics and environment impact. During the cropping cycles, fresh and dry weights, plant nitrogen status (leaves SPAD readings and petiole nitrate content) and plant total N content were determined for calculating the protein content and the plant N uptake. Moreover, at the beginning and the end of the research, chemical soil characteristics and heavy metal levels were also determined. The results indicated that in cocksfoot fertilized with MSW and OPC composts, the mean cumulative dry weight increased by 20.85 and 16.51%, respectively compared to the control, but it was significantly lower than Min treatment. In the alfalfa crop, the mean cumulative dry weight of Control, MSW and OPC treatments were very similar and lower than mineral fertilizer (−7.86, −7.09 and −10.31%, respectively). At the end of the experiment, (2004) the soil total N increased significantly in alfalfa (from 1.32 to 1.45 g kg−1) while no significant difference was found for the cocksfoot. After three years of compost application, the total soil organic carbon increased significantly in both crops (23.98% for cocksfoot, and 43.17% for alfalfa in respect to the control), indicating that MSW and OPC amendments positively affected the organic matter. Furthermore, total organic carbon (in both crops) and humified organic carbon (in alfalfa) were significantly lower in the Contr treatment than on the MSW and OPC treatments.