| Based on National Supervision Base for Aqui-cinnamon Soil Fertility and Fertilizer Benefits in Changping, Beijing (1991-2004), the effect of long-term fertilization on crop yield and soil fertility were investigated. The main results obtained are as follows:1. Crop yield. Compared with the check(CK, no fertilizer application) and single nitrogen fertilizer(N only), combined application of N and P (NP) significantly increased both biomass and grain yield of winter wheat by 400% and summer corn by 100%;Compared with NP ,treatment, N only, combined appplication of P and K(PK), and combined application of N and K(NK), increased crop yield not significantly. The yield increament for winter wheat and summer corn follows the following order: NPK + pig manure(NPKM) or NPK + straw> NPK > NP.2. Fertilizer use efficiency. The total nutrient absorption by crops and apparent nutrient use efficiency (NUE) with combined application of N, P and K were higher than those of the treatment of N only, or N P, N K, and P K. For treatments of NPK+ Straw, NPKM, NPK and NP, the average N use efficiency was 36.2%, 33.0%, 31.8% and 31.2%, and average P use efficiency was 11.5%, 11.6%, 11.8% and 9.5%, respectively. It was indicated that NPK+Straw treatment obtained the highest nutrient use efficiency.3. Soil organic matter. The content of soil organic matter(OM) of NPKM treatment was higher than that of single chemical fertilizer treatment significantly. In comparison with CK, soil OM with treatments of NPK + Straw, NPKM, NPK, NP and N only increased by 7.90%, 14.56%, 6.51%, 5.89% and 2.56%, respectively. Therefore, balanced application of N,Pand K, and combined application of NPK with organic materials play a very important role in improving soil OM status.4. Soil nitrogen. The combined application of NPK with organic materials can increase soil total N content obviously. Both two treatments of NPKM and NPK + straw increased total soil N by 21.11% and 14.35%, respectively, which was higher than that of chemical fertilizer alone markedly. Compared with CK, long-term application of N, NP, and NPK increased soil total N by 10.03%, 8.32% and 8.40%, respectively, while PK treatment decreased soil total N content. Meanwhile, long-term application of N only, NP, NK and NPK increased content of available nitrogen by 17.26%, 21.55%, 23.83% and 26.41 %, separately;Both two treatments of NPKM and NPK + straw were greatly superior to the treatment of those chemical fertilizer alone, with the increment of available nitrogen by 34.97% and 32.96%, respectively.5. Soil phosphorus. In comparison with CK, NPKM increased soil total P content by 52.2%, and that in the treatment of NPK+straw increased by 18.85%, NP, PK and NPK treatment increased by 17.87%, 15.88% and 14.89%, respectively. Above soil total P increases were also higher than those with the treatment of N only or NK. Compared with CK, soil available P increased by 10-fold and 3-fold with the treatment of NPKM and NPK+straw, and 3-5 fold with NP, PK and NPK. Therefore, combined application of chemical fertilizer with organic manure can improve available soil P sink.6. Soil potassium. Application of Chemical fertilizer alone without organic manure can keep the balance of K input and output. Addition of NPK along with pig manure and straw increased soil available K by 16 .0% and 11.4% respectively, compared with CK. The available K declined year by year in the treatments without K fertilizer. Changes of soil slow-released K followed similar trend to the available K. Therefore, long-term application of chemical K fertilizer or its combined application with organic materials can not only meet the K demand by crops, but also improve the soil K supplying capacity.In general, the changes of crop yield, soil fertility and fertilizer use efficiency above indicated that application of chemical fertilizer along with organic materials should be the best fertilization system for Aqui-cinnamon soil.
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