Combined Organic/Inorganic Fertilization Enhance Soil Quality and Increased Yield, Photosynthesis and Sustainability of Sweet Maize Crop

A field experiment was conducted to determine the effects of inorganic and combined organic/inorganic fertilization on growth, photosynthesis and yield of a sweet maize crop (Zea mays L. F1 hybrid Midas), under Mediterranean climatic conditions. A randomized complete block design was employed with four replicates per treatment (inorganic fertilizer (21-0-0), control and 12 combined organic (poultry, cow manure and barley) and inorganic fertilization (synthetic fertilizer: 21-0-0) treatments. The amount of N contributed to the soil via the different fertilization treatments was the same (240 kg N ha-1). Organic soil amendments increased the level of soil organic matter and total nitrogen. The highest height, dry weight, leaf area index and yield were recorded with the cow manure treatments (with or without chemical fertilizer). Moreover, combined organic and inorganic fertilizers resulted in higher increase in photosynthetic rate and stomatal conductance compared with those found under inorganic fertilization. A high correlation coefficient (r=0.926, p<0.001) between yield and photosynthetic rate was found. Sustainability yield indices (sustainable yield index and agronomic efficiency) showed that the maize crop is more stable under combined organic and inorganic fertilization compared with mineral fertilization. Our results indicate that combined organic and inorganic fertilization enhances organic matter in soils and increases yield of sweet maize.