The effect of winery solid waste compost application on maize growth, biomass yield, and nutrient content under greenhouse conditions

A greenhouse study was conducted to assess the fertilizer value and determine the optimum application rate of five winery solid waste (WSW) composts containing varied filter material (FM) mixed proportions with grape marc and pruning canes using maize. The composts comprised of 4, 10, 20, 30, and 40% FM (w/w) designated C4FM, C10FM, C20FM, C30FM, and C40FM, respectively. Application rates of 5, 10, 20, 40, and 80 t ha(-1) were used; while unamended control and inorganic NPK fertilizer treatments were included as references. The results showed that application of composts with 20% FM or more at 80 t ha(-1) significantly increased the dry matter yield more than NPK fertilizer but full potential was not reached due to inadequate nitrogen supply. Maize shoot K content from compost treatments exceeded the critical nutrient level while the shoot Zn content from compost treatments with 20% FM or less also exceeded the critical level. The results revealed that these composts could serve as potential good sources of K and Zn for maize production, particularly, in sandy soils where these nutrients are often reported to be deficient. Quantitative estimate of the optimum rate of the composts for dry matter production ranged from 75 to 307 t ha(-1).