• Authors:
    • Jia, H.
    • Ma, C.
    • Yang, Q.
    • Liu, Z.
    • Li, G.
    • Liu, H.
  • Source: Nongye Jixie Xuebao = Transactions of the Chinese Society for Agricultural Machinery
  • Volume: 38
  • Issue: 12
  • Year: 2007
  • Summary: The present status of dry farming in northern China was analyzed and a three-year rotation tillage method suitable for the ridged cultivation region of northeastern China and the techniques for efficient utilization of natural rainfall in the Loess Plateau region of northwestern China was put forward. The tests conducted in the northeast showed that stalk mulching increased the percentage of soil moisture content by 10% and the content of soil organic matter by 0.06 percentage point after three years, decreased the volume density of soil by 0.09 g/cm 3, chiseling increased the percentage of soil moisture content by 26.2%, and less tillage increased the percentage of soil moisture content by 3 percentage point. The tests conducted in the northwest showed that for winter wheat, the percentage of water storage increased by 18-5%; for spring corn, the percentage of soil moisture content increased by 30%. The stalk mulching tests for two years showed that the content of soil organic matter increased by 0.05%-0.1% and the content of total nitrogen increased by about 0.1 g/kg.
  • Authors:
    • Zhang,X. C.
    • Liu,W. Z.
  • Source: Field Crops Research
  • Volume: 100
  • Issue: 2-3
  • Year: 2007
  • Summary: Matching fertilizer rates with available water supplies in water-scarce environments remains a major challenge for improving water use efficiency and crop yield. The objectives are to (i) develop a new approach to characterizing interrelations of yield ( Y), evapotranspiration (ET), water use efficiency (WUE), and soil fertility using an elasticity index, and (ii) to further derive optimal-coupling domains of water and fertilizer inputs using maize data of 1997 and 1998, as an example. The experiment was an incomplete factorial design with two factors (water supply and fertilizer input) with five levels each, and had a total of 13 treatments with three replicates each. A maize cultivar (Zhongdan 2, Zea mays L.) was grown in a loessial silt loam in the hilly region of the Loess Plateau of China. Irrigation was hand applied at predetermined amounts as needed, and fertilizers including nitrogen, phosphate, and yard manure were applied at planting and jointing at predetermined rates. Approaches on how to use the crop-water production function and elasticity index (EI) to characterize the interrelations of Y, ET, and WUE were presented, and further extended to derive the optimal-coupling domains of water and fertilizer inputs. Yield responses to water and fertilizer inputs followed a quadratic function with a positive interactive term. When constrained by local maximum yields, the optimal-coupling domain took a half-ellipse form with the global maximum WUE and Y (or maximum ET) corresponding to the left and right end points on its long axis. As water supply increased, WUE reached its maximum before yield did. If water supply is limiting, fertilizer rates that maximize WUE rather than yield should be used; otherwise, seeking maximum yield may be desirable. For irrigation management, total water supply to maize should not exceed 550 mm in the region. Furthermore, the optimal domain can be used to determine optimal fertilizer rates for any given water supply, which may be estimated from seasonal climate forecasts in the case of dryland farming or based on available water supply for future irrigation. For a given water supply, fertilizer rates should be between the rate of reaching local maximum WUE and the rate of reaching local maximum yield.
  • Authors:
    • Deng, L.
    • Ren, C. Z.
    • Ma, B. L.
    • Burrows, V.
    • Zhou, J.
    • Hu, Y. G.
    • Guo, L.
    • Wei ,L.
    • Sha, L.
  • Source: Field Crops Research
  • Volume: 103
  • Issue: 3
  • Year: 2007
  • Summary: Increased land degradation and shortage of forage resources for animal production over-winter have accentuated the need for alternative cropping systems in northeast China. While short frost-free period and cool temperatures are major limitations to cereal grain production in the northern regions of China (45degreesN, 122degreesE), crop varieties that are able to produce food and feed in short growing season and tolerant to low temperature may extend the total cropping period. Three hulless oat ( Avena sativa L.) lines, Baiyan 9015, Baiyan 9017 and Baiyan 9044, were bred and tested for 3 years (2004-2006) to determine their suitability for summer seeding in a double cropping system. The new lines were sown both in the spring and summer to provide growers with opportunities to harvest two grain-crops in a year. Averaged across 3 years, Baiyan 9044 produced 2.5 and 1.6 Mg ha -1 yr -1 grain yield when sown in spring and summer, respectively. The new lines seeded in 20th or 21st July and harvested in early October allowed utilization of an average of over 1500 growing degree days (GDDs). For grain yield alone, the net income for two oat crops a year was up to 1390 Chinese yuan (RMB) ha -1, more than that of growing a single oat crop in 3 years, or in most cases, equivalent to monocultured corn ( Zea mays L.) production, the dominant crop in the region. In addition, an average of 5 Mg ha -1 of oat straw was produced as valuable forage fodder for the livestock industry, which was in great demand for over-wintering animals. Furthermore, in the traditional single small grain cereal cropping system, bare ground after harvest leads to severe water and wind erosions. Our results indicate that the new oat lines could be a potential crop for summer seeding, particularly when spring-seeded crops fail due to abiotic (hail, drought, etc.) or biotic (e.g. insects) stresses. The double cropping system provides growers with a potential opportunity to facilitate the farming strategy of food, cash crops and control soil erosion in the region.
  • Authors:
    • Oenema, O.
    • Perdok, U. D.
    • Hoogmoed, W. B.
    • Cai, D.
    • Wang, X.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 79
  • Issue: 1
  • Year: 2007
  • Summary: The rapidly increasing population and associated quest for food and feed in China has led to increased soil cultivation and nitrogen (N) fertilizer use, and as a consequence to increased wind erosion and unbalanced crop nutrition. In the study presented here, we explored the long-term effects of various combinations of maize stover, cattle manure and nitrogen (N) and phosphorus (P) fertilizer applications on maize ( Zea mays L.) yield and nutrient and water use efficiencies under reduced tillage practices. In a companion paper, we present the effects on nutrient balances and soil fertility characteristics. The ongoing factorial field trial was conducted at Shouyang Dryland Farming Experimental Station in northern China from 1993 onwards. The incomplete, determinant-optimal design comprised 12 treatments, including a control treatment, in duplicate. Grain yields and N, P, and potassium (K) uptakes and N, P and K use efficiencies were greatly influenced by the amount of rain during the growing season (GSR), and by soil water at sowing (SWS). There were highly significant interactions between GSR and added stover and manure, expressed in complex annual variations in grain yield and N, P and K use efficiencies. Annual mean grain yields ranged from 3,000 kg ha -1 to 10,000 kg ha -1 and treatment mean yields from 4,500 kg ha -1 to 7,000 kg ha -1. Balanced combination of stover (3,000-6,000 kg), manure (1,500-6,000 kg) and N fertilizer (105 kg) gave the highest yield. Stover and manure were important for supplying K, but the effects differed greatly between years. Overall mean N recovery efficiency (NRE) ranged from 28% to 54%, depending on N source. NRE in wet years ranged from 50% to 90%. In conclusion, balanced combinations of stover, manure and NP fertilizer gave the highest yield and NRE. Reduced tillage with adding stover and manure in autumn prior to ploughing is effective in minimizing labour requirement and wind erosion. The potentials of split applications of N fertilizer, targeted to the need of the growing crop (response farming), should be explored to further increase the N use efficiency.
  • Authors:
    • Qin, Y.
    • Li Fengmin
    • Li, Y.
    • Xiang, S.
    • Cao, X.
    • Wu, T.
  • Source: Dryland crop production: technology breakthroughs and study cases
  • Year: 2007
  • Summary: Fertilization according to soil hydraulic conditions, fertilization in balance of nutrition and fertilization with nutrient use efficiency and sustainability are reestablished as the principles of fertility management in dryland area on the Loess Plateau according to the natural conditions and soil properties. Corresponding techniques to the principles are reviewed and represented in the paper.
  • Authors:
    • Yang, W.
    • Wu, Y.
    • Tu, X.
    • Tu, N.
    • Zhou, W.
    • Yi, Z.
  • Source: Research of Agricultural Modernization
  • Volume: 28
  • Issue: 4
  • Year: 2007
  • Summary: The effects of tillage and no-tillage, and different rates of straw mulching (without, half and full) on soil nutrient content and drought resistance of maize on dry land in Hunan Province (China) were determined. It was found that straw mulching promoted growth and development of maize in normal year (2004) but did not reduce the effect of high temperature and drought and prolonged filling stage 2-4 d in high temperature and drought year (2005). Cultivation measures slightly affected the growth and development of maize. No-tillage prolonged growth duration for around 2 days under high temperature and drought condition. Straw mulching increased plant height, leaf area, dry matter weight, 1000-grain weight and yield. The effects of full-straw mulching were better than those of half-straw mulching. Under the same mulch rates, the effect of tillage was better than no-tillage. The organic matter, readily available K and available P in soil were increased by straw mulching, which was more evident under no-tillage condition although soil organic matter content was slightly decreased without straw mulching. The soil water content was increased by straw mulching, and the effect of full-straw mulching was better than that of half-straw mulching. These results showed that straw mulching can alleviate the harmful effect of drought to a certain extent, and at the same time can increase soil nutrient content. Moreover, the combined effect of straw mulching and no-tillage on increasing soil nutrient content was more evident.
  • Authors:
    • Han, X.
    • Liu, P.
    • Li, L.
    • Huang, J.
    • Sun, O.
    • Zhou, Z.
  • Source: Biogeochemistry
  • Volume: 82
  • Issue: 2
  • Year: 2007
  • Summary: Equilibrium carbon stock is the result of a balance between inputs and outflows to the pool. Changes in land-use are likely to alter such balance, resulting in different carbon stores under different land-use types in addition to the impacts of global climate change. In an agro-pastoral ecotone of Inner Mongolia, northern China, we investigated productivity and belowground carbon and nitrogen stores under six different types of land-uses, namely free grazing (FG), grazing exclusion (GE), mowing (MW), corn plantation (CP), fallow (FL), and alfalfa pasture (AP), and their impacts on litter and fine roots in semiarid grassland ecosystems. We found that there were great variations in aboveground net primary production (ANPP) across the six land-use types, with CP having markedly high ANPP; the FG had significantly reduced soil organic carbon (SOC) and nitrogen stores (SON) to 100 cm depth compared with all other types of land uses, while very little litter accumulation was found on sites of the FG and CP. The top 20 cm of soils accounted for about 80% of the root carbon and nitrogen, with very little roots being found below 50 cm. About 60% of SOC and SON were stored in the top 30 cm layer. Land-use change altered the inputs of organic matters, thus affecting SOC and SON stores accordingly; the MW and GE sites had 59 and 56% more SOC and 61% more SON than the FG. Our estimation suggested that restoring severely degraded and overgrazed grasslands could potentially increase SOC and SON stores by more than 55%; conversion from the native grasses to alfalfa could potentially double the aboveground biomass production, and further increase SOC and SON stores by more than 20%. Our study demonstrated significant carbon and nitrogen storage potential of the agro-pastoral ecotone of northern China through land-use changes and improved management in the context of mitigating global climate change.
  • Authors:
    • Fan, T.
    • Xu, M.
    • Zhou, G.
    • Ding, L.
  • Source: American-Eurasian Journal of Agricultural and Environmental Science
  • Volume: 2
  • Issue: 5
  • Year: 2007
  • Summary: Grain yield trends and changes in Soil Organic Carbon (SOC) from a 26-yr rainfed fertilization trial in Pingliang, Gansu, China, were recorded. Mean wheat ( Triticum aestivum L.) yields for the 18-yr ranged from 1.72 t ha -1 for the unfertilized plots (CK) to 4.65 t ha -1 for the plots that received Manure (M) annually with inorganic Nitrogen (N) and Phosphorus (P) fertilizers (MNP). Corn ( Zea mays L.) yields for the 6-yr averaged 2.43 and 5.35 t ha -1 in the same treatments. Yields declined with year except the CK for wheat. Wheat yields for the N only declined 117.8 kg ha -1 yr -1 that was the highest among all treatments and that for the NP declined 84.7 kg ha -1 yr -1, similar to that of 77.4 kg ha -1 yr -1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments and the declined amounts ranged from 108 to 258 kg ha -1 yr -1 that was much higher than in wheat. SOC gradually increased with time except the CK and N treatments, in which SOC remained almost stable. The SOC increases of 190.1, 166.8 and 164.5 mg C kg -1 yr -1 occurred in MNP and SNP and M treated soils, respectively. About 24% of the total C-input from manure and root residue and about 14% of the total C-input from straw and root residue remained in the soil as organic matter. Losses of 1 t SOM ha -1 were associated with a decrease in wheat yield of approximately 80 kg ha -1, showing the importance of using management practices that minimize losses of SOC in the China Loess Plateau. Grain yield declines were likely related to gradual dry weather and soil available N decline. It is concluded that C sequestration can be enhanced by increasing manure and straw additions in these dryland soils.
  • Authors:
    • Jin, H.
    • Hongwen, L.
    • Xiaoyan, W.
    • McHugh, A. D.
    • Wenying, L.
    • Huanwen, G.
    • Kuhn, N. J.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Soil compaction caused by random traffic or repetitive tillage has been shown to reduce water use efficiency, and thus crop yield due to reduced porosity, decreased water infiltration and availability of nutrients. Conservation tillage coupled with subsoiling in northern China is widely believed to reduce soil compaction, which was created after many years of no-till. However, limited research has been conducted on the most effective time interval for subsoiling, under conservation tillage. Data from conservation tillage demonstration sites operating for 10 years in northern China were used to conduct a comparative study of subsoiling interval under conservation tillage. Three modes of traditional tillage, subsoiling with soil cover and no-till with soil cover were compared using 10 years of soil bulk density, water content, yield and water use efficiency data. Cost benefit analysis was conducted on subsoiling time interval under conservation tillage. Yield and power consumption were assessed by based on the use of a single pass combine subsoiler and planter. Annual subsoiling was effective in reducing bulk density by only 4.9% compared with no-till treatments on the silty loam soils of the Loess plateau, but provided no extra benefit in terms of soil water loss, yield increase or water utilization. With the exception of bulk density, no-till and subsoiling with cover were vastly superior in increasing water use (+10.5%) efficiency and yield (+12.9%) compared to traditional tillage methods. Four years of no-till followed by one subsoiling reduced mechanical inputs by 62%, providing an economic benefit of 49% for maize and 209% for wheat production compared to traditional tillage. Annual subsoiling reduced inputs by 25% with an increased economic benefit of 23% for maize and 135% for wheat production. Yield and power consumption was improved by 5% and 20%, respectively, by combining subsoiling with the planting operation in one pass compared with multipass operations of subsoiling and planting. A key conclusion from this is that annual subsoiling in dryland areas of northern China is uneconomical and unwarranted. Four years of no-till operations followed by 1 year subsoiling provided some relief from accumulated soil compaction. However, minimum soil disturbance and maximum soil cover are key elements of no-till for saving water and improving yields. Improved yields and reduced farm power consumption could provide a significant base on which to promote combined planter and subsoiling operations throughout northern China. Further research is required to develop a better understanding of the linkages between conservation tillage, soil quality and yield, aimed at designing most appropriate conservation tillage schemes.
  • Authors:
    • Li, F.
    • Ma, Q.
    • Wang, Z.
    • Li, X.
  • Source: Soil & Tillage Research
  • Volume: 95
  • Issue: 1
  • Year: 2007
  • Summary: The effects of cultivation and overgrazing on soil quality in arid regions have been rarely addressed. This study investigated the roles of cropping and grazing in soil organic C pools and aggregate stability at 0-20 cm depth by comparing conventional grazing (non-fenced ever), intensive grazing (fenced for 22 years) and cropping (cultivated for 40 years) in the arid Hexi Corridor of northwestern China. Total soil organic C (TOC) under non-fenced grazing was 21.6 g kg-1 (or 52.9 Mg ha-1), which was 19.9% (or 13.2% mass per area) lower than that under fenced grazing, because of lower stable organic C fraction (0.25 mm) in total aggregates and mean weight diameter were 15% and 0.28 mm under cropping, significantly lower than 65% and 3.11 mm under non-fenced grazing and 65% and 2.84 mm under fenced grazing. The aggregates of >1 mm were almost entirely demolished under cropping when subjected to wet sieving. Reduction of soil carbohydrates under cropping was closely related to the decline in aggregate water-stability. The negative effects of cropping on soil organic C pool and aggregate water-stability may suggest that cropping on this arid grassland is not sustainable unless no-tillage is adopted. In favor of increasing soil carbohydrates and maintaining soil aggregation, fenced-grazing would be a better option than cropping and non-fenced grazing for the management of arid grasslands.