Effect of application of Legume green manure and different tillage systems on agronomic, ecological and soil physicochemical aspects in corn cultivation

Corn is considered as one of the most important and strategic cereals in the world that needed a lot of nitrogen fertilizer and often this need is supplied by chemical fertilizers. In addition to the severe need to fossil fuels for chemical fertilizers production, they are also important environmental pollutants (23). Therefore, organic fertilizers such as green manures of legume species can be a good alternative to chemical fertilizers. Also, conservation tillage operations that are accompanied by proper management of crop residues, it is an appropriate solution to prevent the elimination of residues in sustainable agriculture, and plays an important role in improving the physicochemical and biological properties of soil, and can lead to increasing crop yield (22). Therefore, developing and promoting the use of green manure and conservation tillage operations is essential. Therefore, the present study investigates the effect of organic fertilizer application on corn yield under different tillage levels.

This experiment was carried out as split plot in randomized complete block design with three replications at 2018-19 in a farm located in Ghale-No village, Zahak city. Vetch (Vicia villosa) was used as a green manure in this study. The experimental treatments were included two levels of green manure, consumption and no consumption as main factors; and three levels of tillage, no tillage, minimum tillage and conventional tillage as sub plots. In this experiment agronomic traits of plant height, dry and fresh forage yield and seed yield; ecological traits of weeds biomass, photosynthetically active radiation, soil moisture percentage and soil temperature; and some soil physicochemical properties such as soil porosity, bulk density, particle density, organic carbon and nitrogen percentage were evaluated. Data analysis was performed with SAS software.

The experimental results showed that the highest amount of dry and fresh forage yield and seed yield, photosynthetically active radiation, soil porosity percentage, soil organic carbon and nitrogen percentage was obtained from green manure consumption and conventional tillage treatment and there was no statistically significant difference between the consumption of green manure under conventional and minimum tillage conditions. The lowest amounts of the above traits were obtained in the treatment without green manure and no tillage. In addition, the treatment green manure consumption and no tillage system resulted in obtaining the highest soil moisture percentage and the lowest soil temperature. For weed biomass, it was also found that the use of conventional tillage significantly reduces weed biomass, but green manure consumption hadn’t any significant effect on weed biomass.

In this experiment, it was shown that the green manure consumption by increasing the amount of soil organic matter and improving soil structure increased the amount of access to nutrients, especially nitrogen for the plant, which led to enhancing plant yield and growth. Also, increasing the soil porosity and reducing the soil bulk density under the influence of minimum tillage led to soil structure improvement, and it increases the root permeability in soil which this allows the plant to absorb more water and nutrients. Therefore, according to the results of this experiment, it can be suggested that the combination of green manure consumption with minimum tillage can create a good yield in corn cultivation in the study region.