JWSS - Journal of Water and Soil Science

Given the various advantages of applying conservation tillage methods in the agriculture, including reducing the effects of climate change by decreasing the carbon dioxide emissions to the atmosphere caused by carbon sequestration in soil, this study was conducted with two wheat-cotton and wheat-sesame rotations at Agricultural Research Station Bakhtajerd, in Darab, the southeast of Fars Province, which had a warm and dry climate; this work was carried out in a loam soil during four years. The aim of this investigation was to compare the carbon sequestration (CS) in the soil after application of different conservation tillage methods with the conventional method. The results showed that in wheat-cotton rotation, the maximum and minimum amount of CS in the 0-20 cm depth of soil with the average 17.160 and 13.810 t/ha could be obtained by using no-till and conventional tillage, respectively. Therefore, no-till increased CS by 24.26% in wheat and cotton cultivation, as compared to the conventional tillage. The economic value of this CS increment for the environment was $2459 per hectare. In the wheat-sesame rotation, the highest and lowest CS was obtained with an average of 25.850 and 12.505 t/ha in no-till and conventional tillage, respectively. Namely, direct seeding of wheat and sesame increased the CS at the 0-20 cm depth of soil by 107%, as compared to the conventional tillage with the economic value of $9809.5 per hectare. Under similar conditions, in wheat-cotton and wheat-sesame rotations, the conventional methods could be replaced by no tillage.

Today, the use of organic wastes as fertilizers to improve the physical, chemical and biological properties of soil is common. In this study, to investigate the effect of the sewage sludge on the growth and concentration of chlorophyll, nitrogen, phosphorus and potassium in quinoa plant, a factorial experiment was conducted based on a completely randomized design with three replications in a calcareous soil with electrical conductivity of 13.1 dS m^-1. Treatments included three genotypes of quinoa (Red carina, Titicaca, Q29) and three levels of sewage sludge (0, 20 and 40 t ha^-1). The results showed that the effects of the quinoa genotype, different levels of sewage sludge and the interaction of treatments on the root dry weight, shoot P concentration and chlorophyll concentration were significant. Also, the sewage sludge had a significant effect on the shoot length, shoot dry weight and shoot nitrogen concentration. By increasing the level of the sewage sludge, root length, shoot length, shoot dry weight and shoot N concentration were increased, on average, by 44.7 %, 48.8%, 42.0% and 46.6%, respectively. Also, application of 40 t ha^-1 sewage sludge significantly increased the chlorophyll concentration and shoot P concentration in Q29 and Titicaca genotypes. According to the results of this study, application of sewage sludge can increase the growth of quinoa by improving its nutrition.