• Authors:
    • Gao, M.
    • Zhou, T.
    • Zhu, S.
    • Jin, X.
  • Source: Journal of Northwest A & F University - Natural Science Edition
  • Volume: 38
  • Issue: 4
  • Year: 2010
  • Summary: A comparative analysis of the structure and function characteristics and ecological and economic benefits of different agroforestry models in a purple soil area in China was conducted. An agroforestry ecosystem composed of a pear forest and different crops planted under the local forest was taken as the research objective. The emergy analysis method was used to compare the emergy input and output of pear-rapeseed-maize system (model 1), pear-rapeseed-groundnut system (model 2), pear-wheat-maize system (model 3) and pear-wheat-sweet potato system (model 4). Results showed that the energy input structure in the four agroforestry models was similar. The investment of non-renewable emergy took a main proportion in the systems. The human labour emergy and the fertilizer emergy played dominant roles. Model 1 had the highest production efficiency, the most advantageous in price-competition, and the most powerful self-development. Model 4 had the lowest renewable resource utilization, the smallest environment load ratio and the biggest emergy sustainable indices. The net emergy yield ratio and emergy self-support ratio of model 2 were close to that of model 3. However, model 2 had a higher development potential because of its lower environment pressure. The science and technology level of the agroforestry ecosystem in the purple soil area was lower. The input of organic manure should be increased. Model 1 was the best model at present and model 4 was the most potential model for development.
  • Authors:
    • Li, L.
    • Du, F.
    • Zhang, F.
    • Zhang, W.
    • Li, H.
  • Source: Plant Nutrition and Fertilizer Science
  • Volume: 16
  • Issue: 5
  • Year: 2010
  • Summary: Since 2004, China has significantly increased its grain production due to the impetus of strong policy support from the government, including soil testing and fertilizer recommendation. This paper analyzes the changes in fertilizer efficiency in China's grain production systems by comparing the farmers' practice in 2008 and 2001. In the period investigated, chemical fertilizer application rate increased by 5.4% and 29.0% in wheat and maize production, respectively, and decreased by 4.3% in rice cultivation. Total fertilizer consumption increased by 1.3 * 10 6 t on grain crops, but its proportion decreased from 68% to 50% in the total chemical fertilizer consumption of the country. PFP (partial factor productivity, i.e. grain yield divided by the amount fertilizer), used to represent the fertilizer use efficiency of rice, was higher than that of wheat and maize. The PFP of wheat and rice increased from 10.6 kg/kg to 11.9 kg/kg and from 13.9 kg/kg to 15.7 kg/kg, respectively, and that of maize decreased from 13.8 kg/kg to 11.5 kg/kg. The change of planting structure had a strong impact on fertilizer application. The concentration of the production of main cereal crops to the areas with advantageous conditions is believed to be good to the improvement of fertilizer efficiency of cereal crops. On the other hand,the continuous increase in the cultivation area of economic crops will bring additional variables to the changing trend of fertilizer efficiency in China.
  • Authors:
    • Liu, Z.
    • Li, J.
    • Chen, H.
    • Chen, Y.
    • Gao, P.
    • Yang, T.
    • Huete, A.
    • Huang, J.
    • Peng, D.
  • Source: JOURNAL OF ZHEJIANG UNIVERSITY-SCIENCE B
  • Volume: 11
  • Issue: 4
  • Year: 2010
  • Summary: We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts delayed and continuous effects. This study expands on this by mapping the seasonal characterization of NPP and climate variables from space using geographic information system (GIS) technology at the pixel level. Our approach was developed in southeastern China using moderate-resolution imaging spectroradiometer (MODIS) data. The results showed that air temperature, precipitation and sunshine percentage contributed significantly to seasonal variation of NPP. In the northern portion of the study area, a significant positive 32-d lagged correlation was observed between seasonal variation of NPP and climate ( P
  • Authors:
    • Hu, H. Z.
    • Ma, K.
    • Zhang, B.
    • Lan, Z. P.
    • Jiang, X. S.
  • Source: Journal of Beijing Forestry University [and International Journal of AUTOMATION AND COMPUTING 2010 32 (4): 169-174 ISSN: 1476-8186]
  • Volume: 32
  • Issue: 4
  • Year: 2010
  • Summary: A comprehensive analysis was made on the five-year monitoring data of 11 fixed soil erosion monitoring sites of newly established cash crop tree plantations and rehabilitated bamboo forests in eight provinces or autonomous regions of China, which were constructed under the Forestry Development in Poor Area Project (FDPA) financed by the World Bank. The results show that the afforestation and cultivation operations for the cash crop tree plantations and rehabilitated bamboo forests have resulted in soil erosion, but to different degrees. Within the 11 soil erosion monitoring sites, extremely slight or slight soil erosion occurred in six sites and severe soil erosion in three sites during years of frequent and intensive rainfall or on loess hills. The occurrence of soil erosion was lighter on planting sites with broad terrace preparation than on sites with strip or hole preparation. Soil erosion occurred annually on planting sites with continuous intercropping, which showed similar soil erosion modulus. But soil erosion decreased to an extremely low level when, after four years of continuous intercropping, the intercropping stopped. Intercropping also caused relatively strong soil erosion on slope planting sites with strip or hole preparation. For the rehabilitated bamboo forests, soil erosion occurred but in small soil erosion modulus and usually occurred during the first year after rehabilitation and decreased annually with the gradual recovery of undergrowth vegetation. The bamboo shoot harvest in winter increased the occurrence of soil erosion. It is recommended that in the newly established cash crop tree plantations, the best preparation method is by broad terrace type, while avoiding strip or hole preparation. Intercropping can be used under suitable conditions in newly established cash crop tree plantations with broad terrace preparation. For the rehabilitation of low productive bamboo forests, several measures can be adopted to prevent soil erosion, i. e. digging the soil along contours, covering the ground with weeds.
  • Authors:
    • Yang, D. W.
    • Lei, H. M.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 11
  • Year: 2010
  • Summary: In China, croplands account for a relatively large form of vegetation cover. Quantifying carbon dioxide exchange and understanding the environmental controls on carbon fluxes over croplands are critical in understanding regional carbon budgets and ecosystem behaviors. In this study, the net ecosystem exchange (NEE) at a winter wheat/summer maize rotation cropping site, representative of the main cropping system in the North China Plain, was continuously measured using the eddy covariance technique from 2005 to 2009. In order to interpret the abiotic factors regulating NEE, NEE was partitioned into gross primary production (GPP) and ecosystem respiration (R(eco)). Daytime R(eco) was extrapolated from the relationship between nighttime NEE and soil temperature under high turbulent conditions. GPP was then estimated by subtracting daytime NEE from the daytime estimates of R(eco). Results show that the seasonal patterns of the temperature responses of R(eco) and light-response parameters are closely related to the crop phenology. Daily R(eco) was highly dependent on both daily GPP and air temperature. Interannual variability showed that GPP and R(eco) were mainly controlled by temperature. Water availability also exerted a limit on R(eco). The annual NEE was -585 and -533 g C m-2 for two seasons of 2006-2007 and 2007-2008, respectively, and the wheat field absorbed more carbon than the maize field. Thus, we concluded that this cropland was a strong carbon sink. However, when the grain harvest was taken into account, the wheat field was diminished into a weak carbon sink, whereas the maize field was converted into a weak carbon source. The observations showed that severe drought occurring during winter did not reduce wheat yield (or integrated NEE) when sufficient irrigation was carried out during spring.
  • Authors:
    • Liu, W. J.
    • Yang, R.
  • Source: Environmental Earth Sciences
  • Volume: 61
  • Issue: 1
  • Year: 2010
  • Summary: In order to assess the extent of groundwater contamination by nitrate (NO 3--N) and to provide information about the deterioration of the groundwater quality in Zhangye Oasis, Northwest China, a study was conducted in this area. The mean value of NO 3--N concentrations in groundwater samples was 10.660.19 mg l -1. NO 3--N concentrations exceeding 10 mg l -1 (the threshold for drinking water set by the World Health Organization) were found in 32.4% of 71 wells, and were 13, 33.3, 52.4 and 50.0% in the groundwater samples from drinking wells, irrigation wells, hand-pumping wells and groundwater table observation wells, respectively. The result showed that the groundwater samples that had NO 3--N concentrations exceeding the threshold for drinking water were mostly collected from a depth of less than 20 m. Groundwater NO 3--N concentrations in areas used for the cultivation of vegetables, seed maize and intercropped maize were significantly higher than those in urban or paddy areas. NO 3--N contamination of groundwater in areas with sandy soil was more severe than in those with loam soil.
  • Authors:
    • Shi, C. L.
    • Jin, Z. Q.
    • Zhu, D. W.
  • Source: Jiangsu Journal of Agricultural Sciences
  • Volume: 26
  • Issue: 6
  • Year: 2010
  • Summary: In order to explore the effects of climate change on the crop production and agricultural vegetation on the carbon sequestration ability in the Northeast China in the future, the CERES models ran under both baseline weather and climate change scenarios, which were based on 3 global climate models (GCMs) of GISS, GFDL and UKMO, were used to evaluate the effects of climate change on productivities, moisture status and carbon sequestration of soybean, maize, spring wheat and rice in the Northeast China. In 2040, the growth duration of maize and rice would be shortened by 27 d and 29 d, respectively, while 13 d and 9 d were shortened by for soybean and spring wheat, respectively. The simulated soybean biomass under rainfed scenario was averagely 50% higher than that under the baseline weather, while 10% and 6% increments were simulated for irrigated rice and rainfed maize, respectively. The simulated biomass of rainfed spring wheat would be vulnerable to the climate change. The carbon sequestration ability of crops in the Northeast China would be enhanced from 3.82 t/hm 2 to 4.39 t/hm 2 by the climate change. The results indicated that the climate in the Northeast China would display a warm-dry tendency, and the warming climate would shorten the growth period of crops. The soybean productivities would increase significantly in scenarios of doubled CO 2, and rice and maize productivities would increase slightly, while spring wheat productivities would be unstable due to its sensibility to the moisture. Currently, compared with other regions, the crop carbon sequestration ability in the Northeast China was relative weak, while the climate change in the future would be beneficial for the improvement of crop productivities and the strengthening of agricultural carbon pool.
  • Authors:
    • Bastiaanssen, W. G. M.
    • Cheema, M. J. M.
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 10
  • Year: 2010
  • Summary: Water resources planning and management is fundamental for food security, environmental conservation, economic development and livelihoods. In complex basins like the Indus Basin, water is utilized by different land cover and land uses. Up to date information about these Land Use and Land Cover (LULC) classes provide essential information on the water flow path. Traditionally, landscapes are described by cover type. For water management analysis, the information on land use is vital. To this end, a classification of LULC in the Indus Basin (covering 116.2 million hectares of Pakistan, India, China and Afghanistan) has been made. Vegetation index images freely available from SPOT-Vegetation satellite were used to describe the phenological cycle of all agro-ecosystems at a spatial resolution of 1 km x 1 km. An unsupervised clustering technique was adapted to classify 27 land use classes. Ground information and expert knowledge on the growing patterns of crops was used to label the resulting LULC classes. This helped to discern specific crops and crop rotations. An error matrix was prepared using ground truthing data to evaluate the classification accuracy. Existing global, regional and local studies were also considered for validation. The results show an overall accuracy of 77%, with the producer's accuracy being 78% and user's accuracy 83%. The Kappa coefficient (0.73) shows moderate agreement between on ground and satellite derived map. This is deemed sufficient for supporting water management analysis. The availability of major crop rotation statistics and types of forests and savanna is key information for the input data in hydrological models and water accounting frameworks. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Hu, C. S.
    • Ren, T. S.
    • Du, Z. L.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 1
  • Year: 2010
  • Summary: Little information is available about their influences of conservation tillage on the distribution and storage of soil organic C (SOC) and total N in soil profiles in the North China Plain. We investigated the changes in SOC and total N as related to the shift from conventional to conservation tillage using a long-term field experiment with a winter wheat ( Triticum aestivum L.)-corn ( Zea mays L.) double cropping system. The experiment included four tillage treatments for winter wheat: moldboard plow without corn residue return (MP-R), moldboard plow with corn residue return (MP+R), rotary tillage (RT), and no-till (NT). Compared with the MP-R treatment, returning crop residue to the soil (MP+R, RT, and NT) increased SOC and total N in the 0- to 30-cm soil layer, but no distinct changes in SOC and total N concentration were observed among the four treatments at soil depths >30 cm. Compared with the MP+R treatment, the RT and NT treatments increased SOC and total N concentration significantly in the 0- to 10-cm layer but decreased SOC and total N concentration in the 10- to 20-cm layers. As a consequence, soil profile SOC and total N storage did not vary among the MP+R, RT, and NT treatments. Thus under the experimental conditions, conservation tillage (RT and NT) increased SOC and total N contents in the upper soil layers, but did not increase SOC and total N storage over conventional tillage (MP+R) in the soil profile.
  • Authors:
    • Zhang, J. P.
    • Sun, J. S.
    • Liu, Z. G.
    • Qiu, X. Q.
    • Duan, A. W.
    • Gao, Y.
    • Wang, H. Z.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 1
  • Year: 2010
  • Summary: In a field experiment in the Yellow River Basin conducted in 2007 and 2008, it was found that, under full irrigation, the roots of maize not only penetrated deeper than those of soybean but also extended into soybean stands underneath the space between inner rows of soybean. The roots of soybean, however, were confined mainly to the zone near the plants. Horizontal growth of the roots of both the crops was confined mainly to the soil layer 16-22 cm below the surface, a layer that lay above an existing plough pan. Root length density (RLD) was much higher in the top layer (0-30 cm deep) and in the zone closer to the plants. The exponential model proved suitable to describe the RLD vertically and horizontally in both sole cropping and in intercropping.