Effect of Nutrient Management on Yield and Yield Components of Maize (Zea mays L.) influenced by Different Tillage Systems

Conventional tillage systems disturb the soil in the long term and obstruct farmland sustainability. Hence, adoption of conservation tillage systems, for example no tillage and reduced tillage has been widely accepted in the last two decades.
The use of chemical fertilizers has increased in intensive farming systems, but this brings with environmental problems. Nowadays, due to the problems of chemical fertilizers, the use of organic fertilizers such as manure and biochar has been more prevalent in agriculture. Biochar is the product of incomplete combustion of biomass in the absence of oxygen. Its presence in the soil is reported to improve physical and chemical properties and crop yield. In order to evaluate the effect of nutrition management on yield and yield components of corn (Zea mays L.) under different tillage systems, a field experiment was carried out at research farm of Shahrood University of Technology in 2015. The experiment was conducted as a split plot arranged in a randomized complete block design with three replications. The main plots were tillage systems (conventional tillage and reduced tillage) and subplots were control, chemical fertilizer (300 kg.ha-1 urea and 100 kg.ha-1 triple superphosphate), manure (20 t.ha-1), biochar (20 t.ha-1), chemical fertilizer + manure (150 kg.ha-1 urea and 50 kg.ha-1 triple superphosphate and 10 t.ha-1 of manure), chemical fertilizer + biochar (150 kg.ha-1 urea and 50 kg.ha-1 triple superphosphate and 20 t.ha-1 biochar) and manure + biochar (20 t.ha-1 biochar and 10 t.ha-1 of manure). After adding manure, biochar and triple superphosphate, corn was planted on 10 days and urea was used in stages three. At full maturity 10 plants were randomly selected and the biological yield, grain yield, 100-grain weight, ear weight, number of row per ear, number of grains per row, ear length, ear diameter, height and stem diameter were measured. The results showed that the effect of tillage systems and the interaction of tillage systems and nutrient management were not significant on any of the measured traits. Tillage systems affect yield mainly by altering water and nitrate content in soil. The water content and nitrate concentration in the soil had no significant difference between tillage systems (data not shown). As well as tillage systems are site-specific, so the degree of their success depends on soil, climate and management practices. The nutrition management had significant effect on grain nutrients, grain protein, ear characteristics, 100-grain weight, biological yield, grain yield and harvest index. The highest and lowest grain nitrogen, ear weight, biological yield and grain yield were obtained in chemical fertilizer and control, respectively. The chemical fertilizer + manure increased grain nitrogen, ear weight, biological yield and grain yield 13.89, 56.19, 47.04 and 60.41 percent compared to the control, respectively. As well as chemical fertilizer + biochar increased grain nitrogen, ear weight, biological yield and grain yield compared to control 14.81, 52.78, 42.69 and 56.32 percent, respectively. Crops respond to nitrogen fertilization mainly by increasing aboveground and root biomass production. As a result of increasing nitrogen doses, the photosynthetic activity, leaf area index (LAI) and leaf area density (LAD) increase. Providing organic matter and nutrients create better conditions for photosynthesis and plant growth. The increased maize yield in biochar amended soil could be attributed to increased nutrient availability and to improved soil physical properties indicated by decreased soil bulk density. Based on results, the effect of nutrition management was significant on height, stem diameter, grain nutrients, grain protein, ear characteristics, 100-grain weight, biological yield, grain yield and harvest index. Maximum and minimum of stem diameter, grain nitrogen, grain protein, ear characteristics, 100-grain weight, biological yield, grain yield and harvest index were obtained in chemical and control, respectively. Although using of chemical fertilizer had the highest amount of traits, it had no significant difference with chemical fertilizer + manure and chemical fertilizer + biochar. Also, there were no significant effect between conventional tillage and reduced tillage. Therefore, due to the excessive use of nitrogen fertilizer and also due to the negative effects of conventional tillage on the physical, chemical and biological properties of soil, it can be concluded that use of reduced tillage and chemical fertilizer + manure and chemical fertilizer + biochar for corn production is recommended for similar conditions with the study area to reduce both chemical fertilizer and environmental pollution.