Quantitative and qualitative response of maize yield to tillage systems and nitrogen chemical fertilizer

Maize (Zea mays L.) is one of the most important grains in Iran and across the world with a large cultivation area. This crop plays a vital role in industry, human nutrition and animal feed. The relationship between conservation agriculture and tillage methods and nitrogen application is critical to better understanding their role in agro-ecosystem yield. For successful production, tillage systems are one of the essential operations in corn cultivation (Fathi and Zeidali, 2021). Nitrogen is one of the most important nutrients for crops, especially corn, which, if not consumed in sufficient quantities, can limit plant growth. It has been reported that higher or lower nitrogen consumption has a negative effect on crop growth and production (Taheri et al., 2021). There are plenty of attempts to investigate the combining effect of the conservation tillage methods (including reduced or no-tillage) with nitrogen fertilizer application and previous crop residues. This combined strategy could be recommended as one of the most effective approaches to improve maize performance and achieve sustainable agriculture (Kihara et al., 2011). Accordingly, considering the importance sustainable agricultural, it is essential to optimally use nitrogen and also improve soil properties. Therefore, this study aimed to investigate the effect of tillage and nitrogen combined methods on quantitative and qualitative characteristics of corn.

Materials and Methods:

This experiment was performed as a split plot experiment based on randomized complete block design with three replications in 2017-2019 in Darreh-shahr city, Ilam province. Experimental treatments included three levels of tillage including conservation tillage (using compound tillage and farrower), conventional tillage (once reversible plow + once disc + farrower) and intensive tillage (double reversible plow + twice disc + farrower) as the main plot and chemical fertilizer Nitrogen at five levels included no chemical fertilizer application, 50, 100, 150 and 200 kg N ha-1 as sub-plot.

The results showed that the highest grain yield (7615.9 kg ha-1) was obtained in conservation tillage treatment which showed an increase of 22.3% and 5.8% compared to intensive and conventional tillage, respectively. Also, application of 200 kg ha-1 of nitrogen fertilizer had the highest grain yield, which showed a 21% increase compared to the absence of nitrogen. The results of mean comparison showed that in conventional tillage treatment contents of chlorophyll a, b and total showed 8.4%, 23.7% and 12.6% increase compared to intensive tillage, respectively. Comparison mean of nitrogen treatment showed that contents of chlorophyll a, b and total at 150 kg ha-1 of nitrogen fertilizer were 10.92, 3.59 and 14.51 mg g-1 fresh weight, respectively. Consumption of 200 kg ha-1 of nitrogen fertilizer included the highest nitrogen contents of dry matter (1.27%). The results also showed that the highest nitrogen contents of dry matter was assigned to the second year and conservation tillage by 1.25% and the lowest was obtained in the first year and conventional tillage (1.1%). These parameters can be augmented the N and other elements absorption. Moreover, decomposition of organic matters is accelerating in conventional tillage because of more incorporation of residues with the soil. As a result of this process, more nutrient elements were probably absorbed by the roots and enhanced the grain yield, consequently.

According to the results of conservation tillage, it had a more beneficial effect on increasing growth characteristics, yield, yield components and nutrients than conventional and intensive tillage system. It can be stated that the implementation of conservation tillage is able to help absorb nitrogen, which improves yield.