Efficacy of Dairy Cattle Slurry in Preventing Zinc Deficiency of a Silage Corn (Zea mays L.) Grown on a Sandy Soil

Corn silage (Zea mays L.), grown on sandy soil, was severely affected by Zinc (Zn) deficiency stress. Mineral and organic Zn sources were required to prevent this deficiency. The objective of this study is to evaluate the effectiveness of dairy cattle (Bos taurus) slurry as an organic source of Zn in preventing Zn deficiency in corn silage grown on sandy soil. A field experiment was conducted and six rates of dairy cattle slurry were spread just before sowing- 0 or no slurry spread; 50; 100; 150; 200 and 300 t ha-1. These slurry rates were compared to an adequate mineral Zn supply of 5 mg kg-1 applied to soil as (ZnSO4.7H2O). Regression analysis has shown that slurry rates ranging between 50 and 60 t ha-1 had almost similar efficacy to the adequate Zn mineral supply. Both of them corrected Zn deficiency symptoms, enhanced plant growth and increased silage yield by 37.5%, compared to no Zn or slurry applications. A high slurry rate of 280 t ha-1 maximized silage yield but may pose a threat to the environment due to its high content of nitrogen (N). At the next cropping season, a sufficient DTPA residual Zn soil content of 0.9 mg kg-1 was recorded only with a high slurry rate (300 t ha-1).