Study On Effect Of Thiourea Amine On Crop Yield And Ammonia Volatilization In A Rice-wheat Rotation System

New types of nitrogen ?N? fertilizer play important roles in reducing N losses and improving crop yields and N use efficiency ?NUE?, so they are widely used to study the NUE of crop. Thiourea amine ?TA? is a new ammonium N fertilizer, which has some charecters of low costing, environmentally friendly, and increasing crop yield and NUE, therefore the assessment of TA affecting on the environment and agricultural efficiency is necessary. In this study, a field experiment was conducted to determine the effect of three N fertilizers [urea ?U?, ammonium sulfate ?AS? and thiourea ammonium ?TA?] on ammonia volatilization changes in soil nitrogen, crop yield and NUE in a paddy soil. A 3-year experiment was conducated from 2013 to 2015 at Changshu Experiment Station of Institute of Soil Science, CAS in Jiangsu, China. The experiment was included four treatments:no N fertilizer ?CK?, U. AS and TA. The application rates of N fertilizers were 240 kg/hm² and 168 kg/hm² in rice and wheat seasons, respectively. The results were as follows:1. The grain yield of rice for TA was 236 kg/hm² and 341 kg/hm² higher than for U and AS, respectively. Compared with U and AS, TA could increase the aboveground biomass in different growing stages of rice. In the rice season, the N uptake by grain and rice plant for TA were the highest among the three N fertilizer treatments, respectively. The N uptake by grain for TA was 6.94 kg/hm² and 10.77 kg/hm² higher than for U and AS, respectively. The total N uptake for TA was 16.91 kg/hm² and 27.45 kg/hm² higher than for U and AS, respectively. The NUE for TA was 7.05% and 11.44% greater than U and AS, respectively; the agronomic efficiency ?AE? for TA was 0.98 kg/kg and 1.42 kg/kg higher than U and AS, respectively; and there was no significant difference in partial factor production ?PFP? among the three N fertilizers. In the wheat season, the total N uptake for TA was 17.05 kg/hm² and 33.19 kg/hm² lower than for U and AS, respectively; NUE for TA was 10.15% and 19.76% lower than for U and AS, respectively; PFP and AE for TA were 1.79 kg/kg and 3.14 kg/kg, and 1.79 kg/kg and 3.14 kg/kg lower than for U and AS, respectively. Compared with U and AS, TA could improve NUE, AE and PFP of crops in rice season. The NUE of rice was about 42%, so the TA was better for rice than both of U and AS in this region.2. Compared with U and AS, TA increased the soil NH₄⁺-N and NO₃^--N concentrations. In different rice growth stages, ammoniu N of 0-20 cm and 20-40 cm soil layer for TA were 1.13 mg/kg and 2.46 mg/kg, and 1.20 mg/kg and 1.26 mg/kg higher than for U and AS, respectively, and there was no significant difference in soil nitrate-N among three fertilizers. In 2015 rice season, both of soil NH₄⁺-N and NO₃^--N concentrations for TA were highest among four treatments, but there were no significant difference. In different wheat growth season stages, both of soil NH₄⁺-N and NO₃^--N for AS were higher than for U and TA, respectively, and there was no significant difference between U and TA. Most of soil NH₄⁺-N and NO₃^--N were in 0-20 cm soil layer and decreased with increasing soil depth. The reduction in ammonium was greater than nitrate. In crops mature stage, soil nitrate-N was higher than ammonium-N. Both of soil NH₄⁺-N and NO₃^--N for TA were highest among the four treatments in rice season, but Both of soil NH₄⁺-N and NO₃^--N for AS were highest among the four treatments in wheat season. Both of NH₄⁺-N and NO₃^--N concentrations of 0-20 cm soil layer were similar with these of 20-40 cm soil layer after crops harvested.3. The total ammonia volatilization and volatile loss rate were much higher in rice season than in wheat season. In rice season, ammonia volatilization for TA occured mainly in 5-7 days after fertilization. At the same N rate, in 2013 the ammonia volatilization for TA was 5.39% and 13.79% lower than for U and AS, respectively. There were no significant difference in ammonia volatilization among the three N fertilizers in 2014 and 2015, respectively. The amount of ammonia volatilization for TA was lower in both of tillering and panicle stages than for U and AS, respectively; and was lower in the basal period than for AS. but was similar with U in the basal period. After TA applied into paddy field, it could reduce ammonium N, pH and urea concentration in the surface water, these helped to reduce the ammonia volatilization losses. In wheat season, ammonia volatilization for TA was occured primarily within 7-10 days after fertilization, the ammonia volatilization was very low, and it mainly occurred in the basal period. The ammonia volatilization for AS was lower than for U and TA, respectively, but no significant difference was found between U and TA. Therefore, the ammonia losses for TA was lower than for U and AS in rice season, respectively, but there was no difference between U and TA in wheat season.Our results showed that thiourea ammonium had a yield advantage for rice and wheat, compared with U and AS. The price of TA was lower than U, but its N uptake and NUE were significantly higher than both of U and AS. Therefore, the TA was an alternative N fertilizer for rice and wheat in the Taihu Lake region, which could reduce cost of N fertilizer and ammonia losses, and could enhance the NUE of crops.