Effects of combined application of manure and chemical fertilizers on ammonia volatilization loss and yield of winter wheat

ObjectivesThe Huang Huai-Hai Plain (HHP) is an important agricultural production area in North China Plain. The excessive application of nitrogen fertilizers and low nitrogen use efficiency are very common, and nitrogen fertilizer loss and agricultural non-point source pollution are serious. To deal with these problems, the amount of ammonia volatilization loss and its regularity in winter wheat fields under different fertilization treatments were monitored continuously for many years using a long-term fertilization experiment. The purpose of this study aimed to reduce the ammonia volatilization of the HHP, and then provide a scientific basis for improving yield of winter wheat and efficiency of fertilizers based on the long-term fertilizer experiment.

MethodsThe experiment was conducted using lysimeters in 2011–2015 and the tested winter wheat cultivar was SM15. The venting method was used to monitor ammonia volatilization under four fertilization modes (organic manure, M; half organic manure plus half chemical N fertilizer, U + M; urea, U and no N fertilizer, CK) in a winter wheat and summer maize rotation in the North China Plain.

ResultsThe amount of ammonia volatilization varied greatly from 2011 to 2015, with the maximum value of 19.69 kg/hm². The trend of ammonia volatilization rate after the fertilization was similar. The ammonia volatilization in winter wheat mainly occurred within 15 days after the fertilization, and the rate of ammonia volatilization after applying topdressing fertilizer at the jointing stage was significantly higher than that at the seeding stage. The flux of ammonia volatilization was dramatically influenced by fertilizer types and their combination. The amount of ammonia volatilization was 7.26–42.40 kg/hm². The ammonia volatilization loss amounts of the N fertilizer treatments were increased by 1.40–4.84 times compared with the no N fertilizer, which indicated that the application of nitrogen fertilizer could significantly promote the ammonia volatilization in the soil. The rate of N loss was the highest in the U treatment, reaching to 19.5%, that of the M treatment was the lowest, reducing to 5.7%, and that of the U + M treatment was in a middle position which was 12.3%. The rates of nitrogen fertilizer loss in the U + M treatment and the M treatment were decreased by 37.0% and 71.1% for four years compared with the U treatment, respectively, which indicated that the combined application of organic manure and nitrogen fertilizer could significantly inhibit ammonia volatilization. The yield of winter wheat of the U + M treatment was 9461.5 kg/hm² , which was 6.8% and 9.1% higher than those of the U and M treatments, respectively. The nitrogen uptake by grain and absorption of nitrogen in aboveground part of the U + M treatment were also greater, which were 7.1%, 12.6% and 5.4%, 12.9% higher than the U and M treatments, respectively. The nitrogen use efficiency of the U + M treatment was the highest in four years, reaching to 41.96%, which was increased by 16.5%–19.6% and 38.6%–58.7% compared with the U and M treatments, respectively.

ConclusionsIntegrating the grain yield and nitrogen use efficiency, the combined application of organic manure and chemical fertilizers could significantly reduce ammonia volatilization loss and increase grain yield and nitrogen use efficiency, and could achieve synergistic effect of high yield and fertilizer efficiency. Therefore, it can be used as an optimum fertilization method for wheat production in Huang-Huai-Hai region.