| This study aims to investigate effect mechanisms of organic and inorganic combination fertilizer on soil microorganisms, nutrient dynamics and crops growth of rice, spring maize and cabbage. Two years field plot trials were conducted to explain the function mechanism based on soil fertility, nutrient leaching loss and crop physiological characteristics. Nitrogen (N) application amount is used as standard calculation for application amount of rice straw, pig feces, biogas and pig manure composting respectively, phosphorus (P) and potassium (K) application amount of organic and inorganic fertilizer were converted as chemical P and K fertilizer also, aims to equal amounts of nutrient application. There are 8 treatments for two years double cropping rice trial:T1 (10% rice straw N+90% chemical N); T2 (20% pig feces N+80% chemical N); T3 (20% pig manure composting nitrogen+80% chemical N); T4 (20% biogas N+80% chemical N); T5 (10% pig manure composting N+90% chemical N); T6 (30% pig manure composting N+70% chemical N); T7 (chemical fertilizer); CK (no fertilizer). There are 7 treatments for two years spring maize/cabbage rotation trial:Ta (20% pig feces N+80% chemical N); Tb (20% pig manure composting N+80% chemical N); Tc (20% biogas N+80% chemical N); Td (10% pig manure composting N+90% chemical N); Te (30% pig manure composting N+70% chemical N); Tf (chemical fertilizer); CK (no fertilizer). The main results are showed as below:1. Compared with chemical fertilizer application, combination application of organic and inorganic fertilizer increased the number of cultivable bacteria, fungi, actinomycetes, the contents of soil microbial biomass carbon (SMBC) and soil microbial biomass N (SMBN) in paddy and dryland soil are increased also, the potentiality of SMBC transformed into soil organic carbon (SOC) and SMBN transformed into soil total nitrogen(TN) are improved, and accumulation amount of SOC and TN are increased also. And the effects of T3 and Tb treatments are the highest. Two years later, compared with chemical fertilizer treatment, the number of cultivable bacteria, fungi and actinomycetes in paddy soil are increased by 38.07%, 9.9% and 27.01% respectively, and increased by 447.85,60.87 and 160.8 times in dryland soil, the contents of SMBC, SMBN, SOC and TN in paddy soil are increased by 125.62%,134.26%,60.47% and 13.44%, and increased by 97.51%,68.26%, 16.49% and 7.95% in dryland soil respectivly. There are significant positive correlation between SMBC, SMBN and SOC under combinations application of organic and inorganic fertilizer in paddy soil (p<0.01), and positive correlation between SMBC, SMBN, SOC and TN in dryland soil are significant also (p<0.01 or p<0.05).2. Combination application of organic and inorganic fertilizer is benefit to increase of N, P, K and organic matter (OM) content in paddy soil and dryland soil. Combination application of rice straw or pig manure and chemical fertilizer is benefit to increase of available N contents after two years later, P and K accumulation are accelerated by combination application of pig manure composting and chemical fertilizer in paddy soil. K and OM contents are increased with application of pig manure composting increasing. P, K and OM contents are accelerated by combination application of pig manure composting and chemical fertilizer. While the contents TN and available N of Ta are 18.54% and 8.14% higher than Tf.3. Organic N is the main form of N leakage loss from paddy field, while mineral N is the main form of N surface runoff loss from dryland field, and a large portion of mineral N loss are nitrate N in paddy and dryland soil. Reasonable combination application of organic and inorganic fertilizer is benefit to reduce amount of TN, TP, NH4+-N and NO3--N leakage loss from paddy field, and reduce the N and P loss, nutrient uptake of rice, spring maize and cabbage are accelerated and utilization rate of fertilizer is increased. The rice results showed that compared with T7, concentration of TN, TP, NH4+-N and NO3--N leakage loss from paddy field of T3 are obviously reduced, N, P, K uptake are increased by 7.83,0.33 and 3.14 g.kg-1, Utilization rate of N, P, K fertilizer are increased by 5.22%,0.55% and 3.50% respectively. The dryland results showed that N runoff loss of combination application of pig manure composting and chemical fertilizer is more reduced than other treatments. Larger amount of organic fertilizer application with smaller amount of N runoff loss. Phosphorus runoff loss can be reduced by combination application of pig manure composting or biogas by 20% and chemical fertilizer. Compare with Tf, N uptake of Tb and Tc in dryland crops are increased by 20.38% and 34.32% in the second year, and the total N utilization rate during two years are increased by 2.96% and 2.75% respectively.4. Combined application of organic and inorganic fertilizer is benefit to improve photosynthetic characteristics of rice, spring maize and cabbage, nitrate reductase (NR) and phosphate synthase (SPS) activity of functional leaves are increased, and crop yields and quality are improved also. All the above results showed that combination application of pig manure composting and chemical fertilizer has obviously advantages than other treatments. Compared with T7, NR activity of T3 in early rice flag leaves at booting stage is increased by 65.06%, SPS activity is increased by 7.70%, free amino acid contents is increased by 43.87 mg·kg-1, grain yield is increased by 19.65%. The second year of spring maize trial showed that compared with Tf, net photosynthetic rate and transpiration rate of Tb are increased by 13.35% and 9.81%, NR and SPS activities in spring maize functional leaves at filling stage are increased by 17.96% and 9.98%, crude protein and raw starch contents in spring maize corn are increased by 30.4% and 7.48%, while nitrates content is decreased by 49.97%, yield is increased by 7.94%. The second year of cabbage trial showed that compared with Tf, net photosynthetic rate, transpiration rate and stomatal conductance of Tb are increased by 18.35%,4.16% and 1.53% respectively, intercellular CO2 concentration is decreased by 16.48%; NR activity is increased by 69.5% after 10 days transplanting, and SPS activity in functional leaves is increased by 8.24% after 20 days ransplanting; yield is increased by 0.85%. Te is benefit for cabbage quality improvement, soluble sugar and vitamin C content of cabbage are increased by 22.82% and 46.02% respectively, nitrate accumulation is decreased by 29.39%. |
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