• Authors:
    • Ren, Z.
    • Xie, M.
    • Gu, M.
    • Zhang, X.
    • Huang, S.
    • Wu, J.
    • Ju, Y.
    • Zhong, W.
    • Wang, W.
  • Source: Southwest China Journal of Agricultural Sciences
  • Volume: 23
  • Issue: 5
  • Year: 2010
  • Summary: Anthocyanin of color potato was important as its nutritional value, but very little research had been conducted on the influence of cultivation techniques on anthocyanin content of potatoes. In this paper, orthogonal experimental design L 9(3 4) was used to investigate the effect of fertilizers and planting densities on anthocyanin content of color potatoes In different cultivation conditions. The results showed that to obtain the highest anthocyanin content in Ziyun No. 1, optimal cultivation techniques were as follow: at the condition of intercropping with orchard in the shallow valley, optimal average per hectare consumption of fertilizer nutrients was pure P 2O 5 100 kg, the most cost-effective plant density was 50 000 plants/hm 2, with 2 per mil spray concentration of KH 2PO 4; at the condition of individual cropping in the shallow valley, optimal average per hectare consumption of fertilizer nutrients was pure P 2O 5 75 kg, the most cost-effective plant density was 60 000 plants/hm 2, with a 3 per mil spray concentration of KH 2PO 4; at the condition of individual cropping in deep valley between low mountains areas, optimal average per hectare consumption of fertilizer nutrients was pure P 2O 5 100 kg, the most cost-effective plant density was 60 000 plant/hm 2, with 3 per mil spray concentration of KH 2PO 4.
  • Authors:
    • Wang, L.
    • Anjum, S.
    • Xue, L.
    • Zhang, Y,
    • Hu, X,
    • Wang, G.
    • Zou, C.
  • Source: Zhongguo Shengtai Nongye Xuebao / Chinese Journal of Eco-Agriculture
  • Volume: 18
  • Issue: 3
  • Year: 2010
  • Summary: Under the "wheat/maize/sweet potato" tri-crop intercropping system in the southwest China, we researched into the effects of different straw mulching treatments on root morphology, physiological characteristics of transplanted maize at seedling stage. Taking local traditional farming (T) as CK, the other two treatments were straw mulching (TS) and straw mulching plus decomposition catalysts (TSD). The entire experiment lasted for two years. Results show that straw mulching moderately increases root length and root surface area, while significantly increasing root length within 1.0-2.5 mm diameter compared with T treatment. However, there is no significant difference between TSD and TS treatments. Significantly increases in maize seedling root vigor by respectively 19.12%, 27.46%, in root-shoot ratio by 36.72%, 37.50%, and in root biomass by 62.53%, 69.42% are noted under TS and TSD treatments for 2008. Compared with T, the above indicators increase respectively by 17.86% and 25.83%, 31.54% and 33.08%, 65.69% and 77.37% for 2009. Meanwhile, straw mulching enhances soil moisture and nutrient supply. Straw mulching conservation tillage enhances root development and other physiological characteristics under maize intercropping system at seedling stage by changing farmland environment. Straw mulching with decomposition catalysts even performs better.
  • Authors:
    • Zhang, J.
    • Zhang, X.
    • Sun, J.
    • Kang, S.
    • Du, T.
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 1
  • Year: 2010
  • Summary: Water shortage is the major bottleneck that limits sustainable development of agriculture in north China. Crop physiological water-saving irrigation methods such as temporal (regulated deficit irrigation) and spatial (partial root zone irrigation) deficit irrigation have been tested with much improved crop water use efficiency (WUE) without significant yield reduction. Field experiments were conducted to investigate the effect of (1) spatial deficit irrigation on spring maize in arid Inland River Basin of northwest China during 1997-2000; (2) temporal deficit irrigation on winter wheat in semi-arid Haihe River Basin during 2003-2007 and (3) temporal deficit irrigation on winter wheat and summer maize in Yellow River Basin during 2006-2007. Results showed that alternate furrow irrigation (AFI) maintained similar photosynthetic rate ( Pn) but reduced transpiration rate ( Tr), and thus increased leaf WUE of maize. It also showed that the improved WUE might only be gained for AFI under less water amount per irrigation. The feasible irrigation cycle is 7d in the extremely arid condition in Inner River Basin of northwest China and less water amount with more irrigation frequency is better for both grain yield and WUE in semi-arid Haihe River Basin of north China. Field experiment in Yellow River Basin of north China also suggests that mild water deficit at early seedling stage is beneficial for grain yield and WUE of summer maize, and the deficit timing and severity should be modulated according to the drought tolerance of different crop varieties. The economical evapotranspiration for winter wheat in Haihe River Basin, summer maize in Yellow River Basin of north China and spring maize in Inland River Basin of northwest China are 420.0 mm, 432.5 mm and 450.0 mm respectively. Our study in the three regions in recent decade also showed that AFI should be a useful water-saving irrigation method for wide-spaced cereals in arid region, but mild water deficit in earlier stage might be a practical irrigation strategy for close-planting cereals. Application of such temporal and spatial deficit irrigation in field-grown crops has greater potential in saving water, maintaining economic yield and improving WUE.
  • Authors:
    • Hao, M.
    • Fan, J.
    • Malhi, S.
  • Source: Canadian Journal of Soil Science
  • Volume: 90
  • Issue: 3
  • Year: 2010
  • Summary: Nitrate (NO 3-) leaching and water contamination have become a worldwide concern. In this review, some examples are presented to show the extent and magnitude of NO 3- accumulation in the soil profiles and its potential effects on contamination of ground water and surface water under dryland farming in northern China. Climatic and management factors affecting NO 3- leaching are also discussed. In northern China, rainfall is relatively sparse, but the high intensity of precipitation and porous soils play an important role in the accumulation of NO 3N in soil and its subsequent leaching in the soil profile. There is a risk of nitrate accumulation and leaching when high rates of fertilizer N are applied to improve crop yields, and it becomes even worse when conventional land use is changed from cereal crops to vegetable crops and fruit orchards. Under such conditions, shallow ground water might be polluted by NO 3-. This suggests that more attention should be paid to prevent this problem by using best management practices, especially by controlling the amount of N fertilizer input, balanced fertilization, split N application, inclusion of crops with deep taproots in the rotation and minimizing summer fallow (especially tilled) frequency.
  • Authors:
    • Butterbach-Bahl, K.
    • Yao, Z.
    • Wu, H.
    • Sutton, M. A.
    • Han, X.
    • Dannenmann, M.
    • Chen, W.
    • Brüggemann, N.
    • Zheng, X.
    • Wolf, B.
  • Source: Nature
  • Volume: 464
  • Issue: 7290
  • Year: 2010
  • Summary: Atmospheric concentrations of the greenhouse gas nitrous oxide (N2O) have increased significantly since pre-industrial times owing to anthropogenic perturbation of the global nitrogen cycle, with animal production being one of the main contributors. Grasslands cover about 20 per cent of the temperate land surface of the Earth and are widely used as pasture. It has been suggested that high animal stocking rates and the resulting elevated nitrogen input increase N2O emissions. Internationally agreed methods to upscale the effect of increased livestock numbers onN2Oemissions are based directly on per capita nitrogen inputs. However, measurements of grassland N2O fluxes are often performed over short time periods, with low time resolution and mostly during the growing season. In consequence, our understanding of the daily and seasonal dynamics of grassland N2O fluxes remains limited. Here we report year-round N2O flux measurements with high and low temporal resolution at ten steppe grassland sites in Inner Mongolia, China. We show that short-lived pulses of N2O emission during spring thaw dominate the annual N2O budget at our study sites. The N2O emission pulses are highest in ungrazed steppe and decrease with increasing stocking rate, suggesting that grazing decreases rather than increases N2O emissions. Our results show that the stimulatory effect of higher stocking rates on nitrogen cycling and, hence, on N2O emission is more than offset by the effects of a parallel reduction in microbial biomass, inorganic nitrogen production and wintertime water retention. By neglecting these freeze-thaw interactions, existing approaches may have systematically overestimated N2O emissions over the last century for semi-arid, cool temperate grasslands by up to 72 per cent.
  • Authors:
    • Yu Qiang
    • Wang Enli
    • Chen Chao
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 8
  • Year: 2010
  • Summary: In the North China Plain (NCP), while irrigation using groundwater has maintained a high-level crop productivity of the wheat-maize double cropping systems, it has resulted in rapid depletion of groundwater table. For more efficient and sustainable utilization of the limited water resources, improved understanding of how crop productivity and water balance components respond to climate variations and irrigation is essential. This paper investigates such responses using a modelling approach. The farming systems model APSIM (Agricultural Production Systems Simulator) was first calibrated and validated using 3 years of experimental data. The validated model was then applied to simulate crop yield and field water balance of the wheat-maize rotation in the NCP. Simulated dryland crop yield ranged from 0 to 4.5 t ha -1 for wheat and 0 to 5.0 t ha -1 for maize. Increasing irrigation amount led to increased crop yield, but irrigation required to obtain maximum water productivity (WP) was much less than that required to obtain maximum crop yield. To meet crop water demand, a wide range of irrigation water supply would be needed due to the inter-annual climate variations. The range was simulated to be 140-420 mm for wheat, and 0-170 mm for maize. Such levels of irrigation applications could potentially lead to about 1.5 m year -1 decline in groundwater table when other sources of groundwater recharge were not considered. To achieve maximum WP, one, two and three irrigations (i.e., 70, 150 and 200 mm season -1) were recommended for wheat in wet, medium and dry seasons, respectively. For maize, one irrigation and two irrigations (i.e., 60 and 110 mm season -1) were recommended in medium and dry seasons, while no irrigation was needed in wet season.
  • Authors:
    • Dai, Z.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 138
  • Issue: 3-4
  • Year: 2010
  • Summary: The Grain-to-Green Program (GTGP) was initiated in China in 2000 to address environmental degradation. In northern China, the central goal of the program is to entice sustainable transitions in resource uses through subsidizing cropland afforestation and grassland exclosure. This study, based on a household survey in Shabianzi, an agropastoral community in the Mu Us Sandy Land, examines farmers' responses to and the environmental outcome of the GTGP. Results show that through intensification of maize production, farmers were able to assimilate the impact of grassland exclosure, and the new resource use system fosters closer linkage between crop and livestock production. As a result, sheep population in the community shows a steady recovery after the program, hogs experience a sharp increase, while goats register an abrupt decline. Improved household economy resulted from increased livestock offtake rates diminishes pressure on subsistence cultivation, and average household landholding has been stabilized at 1.0-1.2 ha. Grassland exclosure is almost universally violated through surreptitious herding; but grazing intensity has been reduced, which leads to vegetation recovery and an improvement in the local environment. Similar transitions are observable within the Mu Us Sandy Land, demonstrating these successful stories are not site-specific, but represent a general pattern. These "islands of sustainability" stress the importance of pathway(s) undertaken by local farmers in understanding the environmental outcomes of the GTGP. They also suggest that even in an endangered environmental region, opportunities for sustainable resource use are still present.
  • Authors:
    • Krugman, P.
  • Source: The New York Times
  • Year: 2010
  • Authors:
    • Yang, Z.
    • Chen, D.
    • Li, M.
    • Liang, W.
    • Wang, K.
    • Wang, Y.
    • Han, S.
    • Zhou, Z.
    • Zheng, X.
    • Liu, C.
  • Source: Plant and Soil
  • Volume: 332
  • Issue: 1-2
  • Year: 2010
  • Summary: Cotton is one of the major crops worldwide and delivers fibers to textile industries across the globe. Its cultivation requires high nitrogen (N) input and additionally irrigation, and the combination of both has the potential to trigger high emissions of nitrous oxide (N2O) and nitric oxide (NO), thereby contributing to rising levels of greenhouse gases in the atmosphere. Using an automated static chamber measuring system, we monitored in high temporal resolution N2O and NO fluxes in an irrigated cotton field in Northern China, between January 1st and December 31st 2008. Mean daily fluxes varied between 5.8 to 373.0 µg N2O-N m-2 h-1 and -3.7 to 135.7 µg NO-N m-2 h-1, corresponding to an annual emission of 2.6 and 0.8 kg N ha-1 yr-1 for N2O and NO, respectively. The highest emissions of both gases were observed directly after the N fertilization and lasted approximately 1 month. During this time period, the emission was 0.85 and 0.22 kg N ha-1 for N2O and NO, respectively, and was responsible for 32.3% and 29.0% of the annual total N2O and NO loss. Soil temperature, moisture and mineral N content significantly affected the emissions of both gases (p<0.01). Direct emission factors were estimated to be 0.95% (N2O) and 0.24% (NO). We also analyzed the effects of sampling time and frequency on the estimations of annual cumulative N2O and NO emissions and found that low frequency measurements produced annual estimates which differed widely from those that were based on continuous measurements.
  • Authors:
    • Sun, O. J.
    • Wang, E.
    • Luo, Z.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 139
  • Issue: 1-2
  • Year: 2010
  • Summary: Adopting no-tillage in agro-ecosystems has been widely recommended as a means of enhancing carbon (C) sequestration in soils. However, study results are inconsistent and varying from significant increase to significant decrease. It is unclear whether this variability is caused by environmental, or management factors or by sampling errors and analysis methodology. Using meta-analysis, we assessed the response of soil organic carbon (SOC) to conversion of management practice from conventional tillage (CT) to no-tillage (NT) based on global data from 69 paired-experiments, where soil sampling extended deeper than 40 cm. We found that cultivation of natural soils for more than 5 years, on average, resulted in soil C loss of more than 20 t ha-1, with no significant difference between CT and NT. Conversion from CT to NT changed distribution of C in the soil profile significantly, but did not increase the total SOC except in double cropping systems. After adopting NT, soil C increased by 3.15 +- 2.42 t ha-1 (mean ± 95% confidence interval) in the surface 10 cm of soil, but declined by 3.30 ± 1.61 t ha-1 in the 20-40 cm soil layer. Overall, adopting NT did not enhance soil total C stock down to 40 cm. Increased number of crop species in rotation resulted in less C accumulation in the surface soil and greater C loss in deeper layer. Increased crop frequency seemed to have the opposite effect and significantly increased soil C by 11% in the 0-60 cm soil. Neither mean annual temperature and mean annual rainfall nor nitrogen fertilization and duration of adopting NT affected the response of soil C stock to the adoption of NT. Our results highlight that the role of adopting NT in sequestrating C is greatly regulated by cropping systems. Increasing cropping frequency might be a more efficient strategy to sequester C in agro-ecosystems. More information on the effects of increasing crop species and frequency on soil C input and decomposition processes is needed to further our understanding on the potential ability of C sequestration in agricultural soils.