Effects of municipal solid waste compost and chemical fertilizers on concentration some of nutrients in soil, yield and nitrate accumulation in Lettuce (Lectuca Sativa L.) variety of Babel

Evaluation of the possibility of integrated use of organic and inorganic fertilizers or gradual replacement of chemical fertilizers with organic manures is necessary due to environmental issues resulted due to application of chemical fertilizers. well as increasing its quality value. This research was conducted to evaluate the municipal solid waste compost (MSW) as compared to chemical fertilizers on concentration some of nutrients in soil, yield and nitrate accumulation in Lectuce leaf.

This field research was conducted with MSW at 4 levels (0, 10, 20 and 30 t ha-1) and chemical fertilizers at four levels (0, conventional farmers, based on soil test and 25% lower than the soil test), in a factorial experiment based on a randomized complete blocks design with three replications in Kermanshah region during 2014-2015. Seeds of Lectuce were planted in plots. Before seed sowing, physical and chemical characteristics of experimental site soil was analyzed with standard methods. Fertilizers were mixd with surface soil, thoroughly and weed control and sprinkler irrigation was done when nessesary. soil samples at post harvesting stage from each treatment plot was collected for determining Organic Carbon (O.C), N, P, K, Fe, Zn, Mn, Cu, Cd and Pb. Finally, yield, nutrients concentration and Lectuce leaf nitrate rate were measured with conventional methods.

The results showed that the main effects of different amounts of MSW and chemical fertilizers on yield, nitrate rate, nutrients concentration and their interaction effects on yield, nitrate rate was a significant at 1% (P<0.01) and also on the concentration of N, Fe, Zn and Mn in Lectuce leaf at level 5% (P<0.05). The highest yield (35.6 t ha-1) and nitrate rate (749 mg kg-1 DM) was obtained with the application of 10 t MSW ha-1 and chemical fertilizers based on conventional farmers, and lowest of them was obtained with 22.8 t ha-1 and 170 mg kg-1 DM with control treatment, respectively. Also, the main effects of different amounts of MSW and chemical fertilizers on the concentration of most nutrients in soil was a significant at 1% (P<0.01) and their interaction effects on the concentration of O.C, Zn, Fe and Cu at 5% (P<0.05). The highest concentration of Zn, Fe and Cu with the application of 30 t MSW ha-1 and chemical fertilizers based on conventional farmers was observed that their difference compared to the control treatment was 1.28, 3.16 and 1.24 mg kg-1 soil, respectively.

According to the results of this study and considering the environmental problems and nitrate rate in Lectuce leaf, the combined application of 10 t MSW ha-1 and chemical fertilizers 25% lower than the soil test is recommended.