Rational application of nitrogen （N） fertilizers is an important measure to raise N fertilizer recovery rate and reduce N loss.A two-year field experiment of rice-wheat rotation was employed to study the effects of ...Rational application of nitrogen （N） fertilizers is an important measure to raise N fertilizer recovery rate and reduce N loss.A two-year field experiment of rice-wheat rotation was employed to study the effects of N fertilization modes including a N fertilizer reduction and an organic manure replacement on crop yield,nutrient uptake,soil enzyme activity,and number of microbes as well as diversity of microbes.The result showed that 20% reduction of traditional N fertilizer dose of local farmers did not significantly change crop yield,N uptake,soil enzyme activity,and the number of microbes （bacteria,actinomycetes,and fungi）.On the basis of 20% reduction of N fertilizer,50% replacement of N fertilizer by organic manure increased the activity of sucrose,protease,urease,and phosphatase by 46-62,27-89,33-46,and 35-74%,respectively,and the number of microbes,i.e.,bacteria,actinomycetes,and fungi by 36-150,11-153,and 43-56%,respectively.Further,organic fertilizer replacement had a Shannon＇s diversity index （H） of 2.18,which was higher than that of other modes of single N fertilizer application.The results suggested that reducing N fertilizer by 20% and applying organic manure in the experimental areas could effectively lower the production costs and significantly improve soil fertility and biological properties.展开更多
Soil labile (biologically active) organic carbon fractions under different crop rotation systems in Jiangsu Province, China, were investigated after 10 years of rotation. The rotation systems, including green manureri...Soil labile (biologically active) organic carbon fractions under different crop rotation systems in Jiangsu Province, China, were investigated after 10 years of rotation. The rotation systems, including green manurerice-rice (GmRR), wheat-rice-rice (WRR), wheat-rice (WR) and wheat/corn intercrop-rice (WCR) rotations,were established on paddy soils using a randomized complete block design with three replicates. The total organic carbon (TOC), total nitrogen (TN) and water-soluble organic carbon (WSOC) in the soils under different systems were greater in the GmRR and WRR than in the WR and WCR rotation systems because the soils under triple cropping often received more crop residues than the soils under double cropping. Both the WSOC and the microbial biomass carbon (MBC) contents in the soils of the GmRR rotation system were significantly greater than those in the other crop rotation systems, which was due to the return of green manure to the fields of the GmRR rotation system. The results of a 13C nuclear magnetic resonance (13C-NMR) analysis indicated that the structural characteristics of soil WSOC were similar under the four crop rotation systems with carbohydrates and long-chain aliphatics being the major components. Correlation analysis showed that the content of the WSOC was positively correlated with that of the MBC (P ＜0.01),and all had significantly positive correlations with TOC and TN. The coefficients of variation (CVs) for WSOC and WSOC/TOC were greater than the other indices (e.g, MBC, TOC and TN), suggesting that WSOC in the soils was more sensitive to these rotation systems. The results above indicated that the soil amended with green manure could not only increase the usable C source for soil microorganisms, but could also enhance soil organic matter content; hence, rotation with green manure would be a good strategy for sustainable agriculture.展开更多
Soil microbiological and biochemical properties under various field crop rotations such as grains, pastures and vegetables have been studied intensively under short-term period. However, there is limited information a...Soil microbiological and biochemical properties under various field crop rotations such as grains, pastures and vegetables have been studied intensively under short-term period. However, there is limited information about the influence of banana-based rotations on soil organic C, total N(TN), microbial biomasses and enzyme activities under long-term crop rotations. A field experiment arranged in a randomized complete block design with three replicates was carried out at the Wanzhong Farm in Ledong(18?37′–18?38′N, 108?46′–108?48′E), Hainan Province, China, to compare the responses of these soil parameters to long-term(10-year) banana(Musa paradisiaca)-pineapple(Ananas) rotation(AB), banana-papaya(Carica) rotation(BB) and banana monoculture(CK) in a conventional tillage system in the Hainan Island. Soil p H, total organic C(TOC), dissolved organic C(DOC), TN, total P(TP) and available P(AP) were found to be significantly higher(P < 0.01) in AB and BB than CK at 0–30 cm soil depth. Microbial biomass C(MBC) and N(MBN) were observed 18.0%–35.2% higher in AB and 8.6%–40.5% higher in BB than CK at 0–30 cm. The activities of urease(UA), invertase(IA), dehydrogenase(DA) and acid phosphatase(APA) showed a mean of 21.5%–59.6% increase in AB and 26.7%–66.1% increase in BB compared with CK at 0–30 cm. Higher p H, TOC and DOC at 0–10 and 10–20 cm than at 20–30 cm were obtained despite of the rotations. Soil MBC and MBN and activities of UA, IA and DA decreased markedly(P < 0.01) with increasing soil depth in the different rotation soils as well as the monoculture soil. In general, soil microbial biomass and enzymatic activities were more sensitive to changes in banana-based rotations than soil chemical properties, and consequently they were well-established as early indicators of changes due to crop rotations in the tropics.展开更多
基金supported by the National Basic Research Program of China (973 Program,2007CB109308)the National High-Tech R&D Program of China (2007AA06Z332)a special grant of Application of Nuclear Techniques in Agriculture from the Ministry of Agriculture of China (200803034)
文摘Rational application of nitrogen （N） fertilizers is an important measure to raise N fertilizer recovery rate and reduce N loss.A two-year field experiment of rice-wheat rotation was employed to study the effects of N fertilization modes including a N fertilizer reduction and an organic manure replacement on crop yield,nutrient uptake,soil enzyme activity,and number of microbes as well as diversity of microbes.The result showed that 20% reduction of traditional N fertilizer dose of local farmers did not significantly change crop yield,N uptake,soil enzyme activity,and the number of microbes （bacteria,actinomycetes,and fungi）.On the basis of 20% reduction of N fertilizer,50% replacement of N fertilizer by organic manure increased the activity of sucrose,protease,urease,and phosphatase by 46-62,27-89,33-46,and 35-74%,respectively,and the number of microbes,i.e.,bacteria,actinomycetes,and fungi by 36-150,11-153,and 43-56%,respectively.Further,organic fertilizer replacement had a Shannon＇s diversity index （H） of 2.18,which was higher than that of other modes of single N fertilizer application.The results suggested that reducing N fertilizer by 20% and applying organic manure in the experimental areas could effectively lower the production costs and significantly improve soil fertility and biological properties.
基金Project supported by the National Key Basic Research Support Foundation (NKBRSF) of China (No. G1999011809) the National Natural Science Foundation of China (No. 49871044).
文摘Soil labile (biologically active) organic carbon fractions under different crop rotation systems in Jiangsu Province, China, were investigated after 10 years of rotation. The rotation systems, including green manurerice-rice (GmRR), wheat-rice-rice (WRR), wheat-rice (WR) and wheat/corn intercrop-rice (WCR) rotations,were established on paddy soils using a randomized complete block design with three replicates. The total organic carbon (TOC), total nitrogen (TN) and water-soluble organic carbon (WSOC) in the soils under different systems were greater in the GmRR and WRR than in the WR and WCR rotation systems because the soils under triple cropping often received more crop residues than the soils under double cropping. Both the WSOC and the microbial biomass carbon (MBC) contents in the soils of the GmRR rotation system were significantly greater than those in the other crop rotation systems, which was due to the return of green manure to the fields of the GmRR rotation system. The results of a 13C nuclear magnetic resonance (13C-NMR) analysis indicated that the structural characteristics of soil WSOC were similar under the four crop rotation systems with carbohydrates and long-chain aliphatics being the major components. Correlation analysis showed that the content of the WSOC was positively correlated with that of the MBC (P ＜0.01),and all had significantly positive correlations with TOC and TN. The coefficients of variation (CVs) for WSOC and WSOC/TOC were greater than the other indices (e.g, MBC, TOC and TN), suggesting that WSOC in the soils was more sensitive to these rotation systems. The results above indicated that the soil amended with green manure could not only increase the usable C source for soil microorganisms, but could also enhance soil organic matter content; hence, rotation with green manure would be a good strategy for sustainable agriculture.
基金supported by the National Natural Science Foundation of China (No. 41301277)the Natural Science Foundation of Hainan Province, China (No. 310073)
文摘Soil microbiological and biochemical properties under various field crop rotations such as grains, pastures and vegetables have been studied intensively under short-term period. However, there is limited information about the influence of banana-based rotations on soil organic C, total N(TN), microbial biomasses and enzyme activities under long-term crop rotations. A field experiment arranged in a randomized complete block design with three replicates was carried out at the Wanzhong Farm in Ledong(18?37′–18?38′N, 108?46′–108?48′E), Hainan Province, China, to compare the responses of these soil parameters to long-term(10-year) banana(Musa paradisiaca)-pineapple(Ananas) rotation(AB), banana-papaya(Carica) rotation(BB) and banana monoculture(CK) in a conventional tillage system in the Hainan Island. Soil p H, total organic C(TOC), dissolved organic C(DOC), TN, total P(TP) and available P(AP) were found to be significantly higher(P < 0.01) in AB and BB than CK at 0–30 cm soil depth. Microbial biomass C(MBC) and N(MBN) were observed 18.0%–35.2% higher in AB and 8.6%–40.5% higher in BB than CK at 0–30 cm. The activities of urease(UA), invertase(IA), dehydrogenase(DA) and acid phosphatase(APA) showed a mean of 21.5%–59.6% increase in AB and 26.7%–66.1% increase in BB compared with CK at 0–30 cm. Higher p H, TOC and DOC at 0–10 and 10–20 cm than at 20–30 cm were obtained despite of the rotations. Soil MBC and MBN and activities of UA, IA and DA decreased markedly(P < 0.01) with increasing soil depth in the different rotation soils as well as the monoculture soil. In general, soil microbial biomass and enzymatic activities were more sensitive to changes in banana-based rotations than soil chemical properties, and consequently they were well-established as early indicators of changes due to crop rotations in the tropics.
