Management and Reduction of Chemical Nitrogen Consumption in Agriculture

Nitrogen is an effective material for improving the crop production. There is a big concern about rising chemical nitrogen usage as fertilizer in soil, because some forms of nitrogen absorbs in soil and causes an increase of environment and water pollution and decrease fertilizer efficiency. Composted cow manure is an important resource of organic nitrogen which improves the soil conditions. However, low density of composted cow manure and inconstant nutrient content are two factors that limit the application of composted cow manure. The densification technology is an effective solution for both problems. In this research first the capability of single screw extruder for production of fertilizer pellets including composted cow manure and nitrogen fertilizer was studied and then the effect of fertilizer pellet on the reduction of chemical nitrogen consumption was evaluated. The response of basil plants was determined in three treatments: T1 control (no fertilizer), T2 (nitrogen fertilizer) and T3 (pellet). The results showed that pelletization can be used as a proper method for slow-release nitrogen fertilizer;enhance nitrogen uptake and reducing the chemical nitrogen consumption. The results also showed that all basil responses (chlorophyll content, total weight, leaves weight, root weight and leaf area) were significantly affected by application of N fertilizer and pellet. While maximum recorded parameters were observed with application pellet.

Design,construction and performance evaluation of paddy rice solar drum dryer equipped with perforated drum

A solar drum dryer was designed and constructed for paddy drying,including a fixed outer drum and inner perforated drum,which rotated at the desired rotational speed inside the outer drum.The maximum capacity of the dryer was 10000 g.The rotational speed of the inner drum was controlled.The thermal energy required for the dryer was provided by a solar absorber plate.The dryer per-formance was examined at three levels of rotational speed(0.21,0.42 and 0.84 r.p.m.),drum slope(1°,1.5°and 2°)and air velocity(1.7,1.8 and 1.9 m.s^(-1)).The diameter of the drum was the geometrical parameter that affected the movement of the particles and the ratio of the particle diameter to the drum diameter changed with the change in the drum diameter.Therefore,increasing the diameter of the drum caused a reduction in the repose angle of the paddy without any effect on the filling angle.The displacement of the product along the drum increased with increasing slope and rotational speed.At the lowest air velocity,the time required to remove moisture(<13%)was less.The results showed a significant reduction in cracked brown rice for the paddy dried by the drum dryer at 43-46℃ compared with those dried using a batch dryer.The highest stress-cracking index(11)was observed for the paddy with an initial moisture of 16%.The results showed that for proportional final moisture content,a longer drum should be considered to intensify the slope and rotational speed of the inner drum.