Effect of deficit irrigation, fertilizers and vermicompost on forage maize (Zea mays L.)

Drought is one of the most important factors limiting corn production in the world. On the other hand, the use of renewable resources and inputs such as vermicompost is one of the principles of sustainable agriculture. Therefore, in order to investigate the effect of deficit irrigation, chemical fertilizers and vermicompost an experiment has been performed in the form of split split plots in a randomized complete block design with 3 replications for two years (2017 and 2018) in Kermanshah Agricultural Research and Training Center. Irrigation treatment include optimum, 80% and 60% of water requirement. Chemical fertilizer include 100% and 50% recommended and vermicompost include 0, 2, 4,and 6 ton ha-1 arranged as main plots, sub plots, and sub sub plots, respectively. Results show that leaf area index is decreased from 4.51 to 1.6 from normal irrigation to intense drought stress. The highest yield of fresh forage (82.5 ton ha-1) is obtained in optimal irrigation treatment and combined use of 100% chemical fertilizer and 6 ton ha-1 of vermicompost and the lowest rate (30.1 ton ha-1) is related to 60% water requirement and no use of vermicompost chemical fertilizers. At all irrigation tratments, the percentages of forage protein increase with the use of fertilizers and vermicompost, and the highest percentage of forage protein (10.2%) is obtained in complete irrigation treatment and 100% fertilizer application and 6 ton ha-1 vermicompost. Based on the results in irrigation treatment by 60% of water requirement and application of 50% of chemical fertilizer, application of vermicompost at the rate of six tons per hectare, compared to no application, increases fresh forage by 26.26% and protein by 6.9%.