| Due to the production strength and high intensive degree of farming and breeding in the Chengdu plain area, planting and breeding produced a large amount of waste, and long-term separation of planting and breeding industry causes the inefficient resources use, which would trigger a series of regional environmental hazards. Therefore, it was very important to investigate the crop growth response to the pig manure application, the characteristics of nitrogen uptake, translocation and utilization in the farmland soil under rice wheat rotation system in Chengdu plain. This would provide a reference for revealing the reasonable relationship between cultivation and waste in regional farmland, which has great significances for ensuring healthy and sustainable development of resources and environment in Chengdu plain.(1) In this study, field experiments were carried out to ascertain the quantity of straw, including the following treatments such as the control (No fertilizer application), the half amount of straw application, the total amount of straw application,1.5 times of the total amount straw application. Compared with the controls, different levels of straw incorporation can increase the grain yields about 8.4%-19.6% in wheat and 4.3%-17.1% in rice. The yield-raising range of wheat increased along with the increasing amount of straw application, whereas the yield-raising range of rice reduced with the amount of straw increasing. Likewise, straw incorporation promoted the growth of wheat and rice and increased nitrogen uptake and nitrogen accumulation in grain. During the period of planting wheat, the N uptake and grain nitrogen accumulation increased along with the increasing amount of straw. During the period of planting rice, straw incorporation inhibited rice growth and N uptake before the jointing stage, but promoted the growth and N uptake after the stage. The N uptake and grain nitrogen accumulation of rice reduced along with the increasing amount of straw. The grain yield, N fertilizer use efficiency and agronomic N use efficiency in straw incorporation treatments were higher than that of control by 10%-13.8%,19.5%-26.7%, and 6.71-8.21 kg/kg in the wheat-rice rotation system. Half amount of straw incorporation was the most advantageous treatment to enhance the grain yield and nitrogen use efficiency among the all treatments. There were no significant difference in yield and nitrogen use efficiency between half amount and full amount of straw application. Taking the stock of straw resources, the crop yield and nitrogen use efficiency into consideration, we suggested that the full amount of straw incorporation is suitable for crop production under rice-wheat rotation system in Chengdu plain.(2) In order to ascertain the best dosage of pig manure under rice-wheat rotation system in Chengdu plain, The field experiment was conducted with 7 treatments:No fertilizer(TO), No nitrogen(T1),100% of fertilizer nitrogen(T2),25% pig manure nitrogen plus 75% fertilizer nitrogen(T3), 50% pig manure nitrogen plus 50% fertilizer nitrogen(T4),100% pig manure nitrogen(T5),150% pig manure nitrogen(T6),200% pig manure nitrogen(T7). The crop growth response to the pig manure application, the characteristics of nitrogen uptake, translocation and utilization was investigated in the farmland soil. Result showed that:Compared to T1, The rice growth of T5、T6 and T7 significantly inhibit before the jointing stage. Along with the growth progress, a promotion for the wheat growth was observed. Compared to T1, the grain number per spike number and the number of effective spike were significantly increased by T4 treatment, and the yield of grain was increased, the recovery efficiency, the harvest index and the partial factor productivity of nitrogen in the treatment of T4 were the best in the rotation system. And when pig manure nitrogen replacement is more than 100%(T5,T6,T7),the grain yield and harvest index of wheat and rice significantly decreased, but after the treatment, its soil acid hydrolysis, amino nitrogen, ammonia nitrogen and nitrate nitrogen is significantly higher than T1, which improve soil fertility, but increase the risk of nitrogen loss, this research suggested that the treatment of 50% manure plus 50% nitrogen fertilizer is a good fertilization for rice-wheat rotation area in Chengdu Plain(3) Straw incorporation as a production practice has been widely used in the crop production of the Chengdu plain. Therefore, To ascertain the dosage of pig manure for the protection of crop production and avoid the environmental risk is very important under straw incorporation conditions in Chengdu plain,The field experiment was conducted with 7 treatments:no nitrogen (TO), No nitrogen(T1S),100% of fertilizer nitrogen (T2S),25% pig manure nitrogen+75% fertilizer nitrogen (T3S),50% pig manure nitrogen+50% fertilizer nitrogen (T4S),100% pig manure nitrogen(T5S), Under the total amount of straw to field conditions, the influence of different amount of manure on growing rice and wheat crops is very significant. Compared toT2S T5S inhibited the growing of rice at the early stage, which showed the decreased of rice height and biomass. While the effects on wheat season was in contrast. In terms of the produce, the treatment of T4S has significantly increased the grain yield of rice about 4.81%. On the counter, T5S induced the yield to decline about 5.13% in the same season. The harvest index was significantly lower than before with a mount of straw. The grain yield of wheat with increasing amounts of pig manure will increase, the treatment that 50% manure replace nitrogen fertilizer had the highest increase yield 5.3% which compared with the comparison in entire rice-wheat rotation, this treatment increased rice and nitrogen absorbing in various growth stages. Besides, that increased the nitrogen distribution ratio in rice-wheat and nitrogen apparent utilization of rice grains, agronomic efficiency, partial productivity, this treatment also improved soil ammonium nitrogen concentration in the early stage of rice season and showed beneficial stored capability of nitrogen and induced the loss risk of nitrogen. This study suggested that the response of nitrogen forms on manure inputs was not significant. This research suggested that the treatment of 50% manure plus 50% nitrogen fertilizer is a good fertilization for rice-wheat rotation area in Chengdu Plain under the total amount of straw to field conditions. |
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