- Authors:
- Song, C. C.
- Su, Y. H.
- Yu, Y. Q.
- Zhang, W.
- Sun, W. J.
- Huang, Y.
- Source: Global Change Biology
- Volume: 16
- Issue: 2
- Year: 2010
- Summary: It has been well recognized that converting wetlands to cropland results in loss of soil organic carbon (SOC), while less attention was paid to concomitant changes in methane (CH4) and nitrous oxide (N2O) emissions. Using datasets from the literature and field measurements, we investigated loss of SOC and emissions of CH4 and N2O due to marshland conversion in northeast China. Analysis of the documented crop cultivation area indicated that 2.91 Mha of marshland were converted to cropland over the period 1950-2000. Marshland conversion resulted in SOC loss of similar to 240 Tg and introduced similar to 1.4 Tg CH4 and similar to 138 Gg N2O emissions in the cropland, while CH4 emissions reduced greatly in the marshland, cumulatively similar to 28 Tg over the 50 years. Taking into account the loss of SOC and emissions of CH4 and N2O, the global warming potential (GWP) at a 20-year time horizon was estimated to be similar to 180 Tg CO2_eq. yr-1 in the 1950s and similar to 120 Tg CO2_eq. yr-1 in the 1990s, with a similar to 33% reduction. When calculated at 100-year time horizon, the GWP was similar to 73 Tg CO2 _eq. yr-1 in the 1950s and similar to 58 Tg CO2_eq. yr-1 in the 1990s, with a similar to 21% reduction. It was concluded that marshland conversion to cropland in northeast China reduced the greenhouse effect as far as GWP is concerned. This reduction was attributed to a substantial decrease in CH4 emissions from the marshland. An extended inference is that the declining growth rate of atmospheric CH4 since the 1980s might be related to global loss of wetlands, but this connection needs to be confirmed.
- Authors:
- Source: Better Crops with Plant Food
- Volume: 94
- Issue: 4
- Year: 2010
- Summary: In the north China plain, the amount of N fertilizer and irrigation application in greenhouse vegetable systems is about three to five times that in conventional cereal systems. Over a decade of shifting from the conventional cereal systems to greenhouse vegetables, the capacity for nutrient cycling within these greenhouse systems has fallen. Additionally, the content of inorganic C in the soil profile under greenhouse systems has shown a dramatic decline.
- Authors:
- Christie, P.
- Streck, T.
- Li, L.
- Qin, Z. C.
- Ingwersen, J.
- Ju, X. T.
- Qiu, S. J.
- Zhang, F. S.
- Source: Soil & Tillage Research
- Volume: 107
- Issue: 2
- Year: 2010
- Summary: In recent years large areas of conventional cereal production in China have been transferred to greenhouse production with huge excessive nitrogen (N) fertilizer application and massive irrigation. However, the effects of this change in land use on soil carbon and nitrogen pools remain to be explored. Here we report a comparative study in which paired soil samples were taken from four greenhouses and from adjacent conventional cereal fields. Soil organic carbon (SOC), carbonate carbon (IC), total nitrogen (TN) and mineral nitrogen (N min) to 100 cm depth and the soil active organic pools, including particulate organic matter (POM), soil microbial biomass (SMB) and dissolved organic matter (DOM), to 0-40 cm depth were determined. The natural isotopic signatures of SOC, TN and POM were also analyzed. In both production systems all of the carbon and nitrogen pools in the surface soil (0-10 cm) were greater than deeper in the soil profile except for dissolved organic nitrogen (DON) and NH 4-N. SOC and TN and dissolved organic carbon (DOC) concentrations were higher in the greenhouse system than in conventional cereal soils ( P>0.05). A similar trend was found for POM ( P0.05) and IC in the greenhouse system showed a dramatic decline. The SOC/TN ratios of different pools in the greenhouse soils were lower than in the conventional cereal system ( P>0.05). The SOC/TN ratio ranged from 8.4 to 10.0 in greenhouse soils and 8.5 to 11.7 in the cereal soils. At each depth POM content in the greenhouses (1.5-7.1 g kg -1) was significantly greater than that in the field soils (0.8-2.9 g kg -1) ( P
- Authors:
- Wang, L.
- Chen, Z.
- Chen, X.
- Wan, Y.
- Yang, W.
- Gong, W.
- Yan, Y.
- Source: PLANT PRODUCTION SCIENCE
- Volume: 13
- Issue: 4
- Year: 2010
- Summary: The relay strip intercropping system of wheat-corn-soybean is widely used in southwest China. However, it is hard to obtain a stable production of soybean with this system, since soybean plants grow under shading by corn; the stems are thinner and susceptible to lodging. We examined the effects of seed treatment with uniconazole powder (0, 2, 4 and 8 mg kg -1 seed) on the growth of soybean seedlings under relay strip intercropping, some morphological characteristics and yield. The seedling height, first internode length, cotyledonary node height and leaf area per plant were decreased, while the stem diameter, root dry weight, shoot dry weight, root volume, leaf greenness and root to shoot dry weight ratio were increased by uniconazole treatment. The root vigor and root active absorption area were also increased significantly by uniconazole treatment. Moreover, 2 and 4 mg kg -1 uniconazole powder treatment increased shoot dry weight, number of pods per plant, number of seeds per pod and seed yield significantly. Thus, the results suggested that seed treatment with uniconazole powder at a suitable concentration can improve soybean seedling growth, resist the lodging and also increase the seed yield under shading by corn in relay strip intercropping system.
- Authors:
- Huang, G.
- Chai, Q.
- Yang, C.
- Source: Zhongguo Shengtai Nongye Xuebao / Chinese Journal of Eco-Agriculture
- Volume: 18
- Issue: 4
- Year: 2010
- Summary: A field experiment was carried out to investigate the effect of alternative irrigation on water consumption, yield and water use efficiency ( WUE) under wheat-maize intercropping in the oasis region of Shiyang River Basin, Gansu Province. The results indicate that evaporation for alternative irrigated intercropping system (AI) decreases by 44.0 mm compared to conventional irrigated intercropping system (CI). Water consumption under AI also increases by 15.4 mm while yield and WUE are respectively enhanced by 13.92% and 9.21% compared to CI. All these results show that alternative irrigation is an effective and practicable way to improve yield and WUE of wheat-maize intercropping. Although evaporation and water consumption in alternative irrigated intercropping system increase with increasing irrigation quota, overall WUE actually decreases.
- Authors:
- Yang,C. H.
- Chai,Q.
- Huang,G. B.
- Source: Plant Soil and Environment
- Volume: 56
- Issue: 6
- Year: 2010
- Summary: A field experiment was conducted to investigate the effects of alternate irrigation (AI) on root distribution and yield of wheat ( Triticum aestivum L.)/maize ( Zea mays L.) intercropping system during the period of 2007-2009 in an oasis of arid north-west China. Five treatments, i.e. sole wheat with conventional irrigation (W), sole maize with alternate irrigation (AM), sole maize with conventional irrigation (CM), wheat/maize intercropping with alternate irrigation (AW/M), and wheat/maize intercropping with conventional irrigation (CW/M). The results showed that root growth was significantly enhanced by alternate irrigation (AI), root weight density (RWD), root length density (RLD) and root-shoot ratios (R/S) in AI treatments were all higher than those in conventional irrigation (CI) treatments. Moreover, intercropped wheat and maize also had a greater root development at a majority of soil depths than wheat and maize in monoculture. In three years, AW/M always achieved the highest total seed yield under different treatments. Higher yield and reduced irrigation resulted in higher water use efficiency (WUE) for the AW/M treatment. Our results suggest that AI should be a useful water-saving irrigation method on wheat/maize intercropping in arid oasis field where intercropping planting is decreased because of limited water resource.
- Authors:
- Source: Scientia Agricultura Sinica
- Volume: 43
- Issue: 1
- Year: 2010
- Summary: Objective: The aim of this study was to investigate the effects of weak light on the photosynthetic characteristics of peanut leaves at the seedling stage and to offer a theoretical basis for the programming of peanut intercropped with wheat. Method: Fenghua 1 was grown in an experiment with four shading treatments (CK, in which the plants were grown under natural light, and 27% shading, 43% shading, 77% shading) and the investigation was carried out at seedling stage using black sunshade net. The chlorophyll content, net photosynthetic rate, photosynthetic curve, fluorescence parameters and photosynthetic enzyme activities were tested. Result: Shading treatment significantly reduced the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO 2 concentration (Ci), light compensation point, light saturation point, CO 2 compensation concentration, CO 2 saturation concentration, carboxylation efficiency, RUBPCase and PEPCase activities along with the shading degree but increased the chlorophyll content, apparent quantum yield, and Phi PS II and Fv/Fm. Real-time low light intensity and long-term shading treatment depressed photosynthetic enzyme activities jointly. Conclusion: Shading at seedling stage depressed Pn significantly, which induced by stomatal limitation and non-stomatal factors (such as decline of photosynthetic ability of mesophyll cell, changes of absorbed light allocation of PS II), improved the capacity of utilization of weak light. Shading of 27% had less influence, and therefore can program plant the standards of intercropping system of wheat and peanut.
- Authors:
- Dong, G.
- Chen, Z.
- Wu, Z.
- Sun, C.
- Chen, L.
- Zhang, Y.
- Source: Plant Soil and Environment
- Volume: 56
- Issue: 11
- Year: 2010
- Summary: Agricultural practices that reduce soil degradation and improve agriculture sustainability are important particularly for dry hilly land of Chaoyang County in the Liaoning Province, North-east China, where cinnamon soils are widely distributed and mainly for wheat production. The impacts of 10-year cropping systems (wheat-cabbage sequential cropping, wheat-corn intercrop, wheat-sunflower rotation, wheat-soybean rotation) on soil enzyme properties of surface-soil (0-20 cm) were studied. Total carbon, nitrogen, phosphorus and sulfur, and nine soil hydrolases related to nutrient availabilities (beta-galactosidase, alpha-galactosidase, beta-glucosidase, alpha-glucosidase, urease, protease, phosphomonoesterase, phosphodiesterase, arylsulphatase) and five enzymes kinetic characters were examined. Wheat-corn intercrop systems had higher total C, total N, total P and total S concentrations than wheat-soybean and wheat-sunflower rotation systems. Most test enzyme activities (alpha-galactosidase, beta-galactosidase, alpha-glucosidase, beta-glucosidase, urease, protease, phosphomonoesterase and arylsulphatase) showed the highest activities under wheat-corn intercropping system. Urease, protease and phosphodiesterase activities of wheat-cabbage sequential cropping system were significantly higher than two rotation systems. The maximum reaction rates of enzymes ( Vmax) were higher than apparent enzyme activity, which suggests larger potential activity of enzymes, while not all kinetic parameters were adaptive as soil quality indicators in dry hilly cinnamon soil.
- Authors:
- Sun, Y.
- Zhao, Y.
- Wu, P.
- Cui, H.
- Chen, Z.
- Source: Soil & Tillage Research
- Volume: 110
- Issue: 2
- Year: 2010
- Summary: Wind erosion near soil surface is one of the major causes of farmland degradation and desertification in arid and semiarid areas. Intercropping wheat and potato can effectively reduce wind erosion, soil desertification and degradation. In this paper, a quantitative research on effective resistance width to wind erosion for the wheat and potato intercropping farmland was performed using several 8-channel wind speed samplers and a movable wind tunnel. As can be seen from the test results, the effective width to control wind erosion for conventional tillage strips on wheat and potato intercropping farmland was lower than or equal to 5 m as the wind speed at 2 m height was 6-7 m.s -1. Moreover, the effective width to control wind erosion of conservation tillage strips on wheat and potato intercropping farmland should be greater than or equal to 5.5 m. Therefore, wheat and potato intercropping with suitable strip width is a cropping mode that not only protects farmland soil from wind erosion to the utmost but also satisfies the requirements of regional planting structure.
- Authors:
- Xue, X.
- Chen, G.
- Hu, Y.
- Ren, C.
- Eneji, A.
- Islam, M.
- Source: Journal of Agriculture, Biotechnology and Ecology
- Volume: 3
- Issue: 3
- Year: 2010
- Summary: Oat is an important grain and forage crop and is now being cultivated as a promising forage crop in northern China. Increased land degradation and shortage of forage resources for animal production over-winter have accentuated the need for alternative cropping systems in arid regions of northern China (
