• Authors:
    • Jia, H.
    • Chen, Z.
    • Ma, C.
    • Yang, Q.
    • Liu, Z.
    • Li, G.
  • Source: Nongye Jixie Xuebao = Transactions of the Chinese Society for Agricultural Machinery
  • Volume: 39
  • Issue: 11
  • Year: 2008
  • Summary: This paper describes the tillage technologies for the tillage system of soil water storage and preservation in the area of dry farming of northern China, with surface mulching, reduced-till and no-till as the core technologies, based on combined operations, to achieve the goal of soil water storage and preservation and improving soil fertility. It summarizes six innovative technologies involving the combined stalk and stubble management technology, in which the stalk and stubble of corn can be broken and partially buried in soil at one time; the universal technology for rototilling and stubble breaking, in which the two operations, can be done on the same blade rotor and disc; the strip reduced-till (no-till) precision seeding technology, in which less-tillage (or only furrowing) is needed in the seed bed; the ridging and film-side furrow sowing technology, in which the ridge is covered with the film and seeds are sowed in the furrow; the mechanical bionic resistance reduction technology, which uses the soil working tool designed based on bionics; and the no-till planting and blockage prevention technology, in which no-till planting is conducted in the residue free seed bed. It also shows the composition diagram of the farming system.
  • Authors:
    • Li, S.
    • Zhao, M.
    • Zhen, X.
    • Zhou, J.
    • Wang, C.
  • Source: Journal of Northwest A & F University - Natural Science Edition
  • Volume: 36
  • Issue: 1
  • Year: 2008
  • Summary: An experiment was conducted to investigate the effects of cultivation methods and N rates on N accumulation, distribution and utilization efficiency of winter wheat on manual loessial soils under the winter wheat-summer maize cropping rotation system. The treatments comprised 4 different cultivation methods, i.e. control (C), supplementary irrigation (SI), straw mulching (SM) and furrow planting (FP), and 3 N rates, i.e. 0, 120 and 240 kg/hm 2. Compared with the other 3 cultivation methods, the N residue in leaf and stem of wheat after harvesting was lower in the SI cultivation method, so was the rate of N residue to total N accumulation in the crop. However, the rate of N residue in grain to the N accumulated in shoot was increased. As the application rates of N increased, the N accumulation in leaf, stem, glume and rachis, and grain of wheat was significantly increased. When the N application was increased from 120 to 240 kg/hm 2, the N accumulation in wheat leaf, stem, and glume and rachis was increased after harvesting. However, the N accumulation in grain did not increased significantly. The application of N did not show significant effect on the distribution of N in the different organs of wheat. As the application rates of N increased, the N recovery, agronomic efficiency and physiological efficiency decreased. Compared with the other cultivation methods, the N recovery, agronomic efficiency and physiological efficiency of the SI pattern were higher during the 2 continuous years; the changes in the N efficiency indices of the other 3 cultivation methods varied in different years.
  • Authors:
    • Xia, J.
    • Wu, D.
    • Yu, Q.
    • Wang, E.
  • Source: International Journal of Climatology
  • Volume: 28
  • Issue: 14
  • Year: 2008
  • Summary: The North China Plain (NCP) is the largest agricultural production area in China. The extensive use of groundwater for irrigation agriculture under variable climatic conditions has resulted in the rapid decline of the groundwater table especially in areas north of the Yellow River, leading to hydrological imbalance and unsustainable agricultural production. This article analyses the sustainable level of vegetation/crop water use under the NCP climate by mimicking the evapotranspiration of a natural forest ecosystem. Such a system would have a mean annual evapotranspiration ranging from 470 mm/year in the northern to 910 mm/year in the southern part of the plain, leading to a mean annual water excess (rainfall minus evapotranspiration) ranging from 21 to 124 mm/year. The natural forest ecosystem would use less water than the current wheat/maize double cropping system. To mimic the water use of the natural system, dryland farming has to be practiced, and wheat and maize crops would have a water deficit of 90-435 and 0-257 mm/year, respectively. Under average conditions, this would mean that all the areas north of the 36 degrees N line have to abandon winter wheat production. Stopping irrigation will lead to significantly lower wheat yields (average yield 0.8 t/ha in the north to 5.2 t/ha in the south) and increased variability in wheat and maize yield both interannually and spatially. Better management practices, such as opportunity cropping (what and when to crop depending on climate and soil conditions rather than a set annual cycle), better use of climate forecast information to direct decision making, are required in order to achieve maximum return in good years while minimizing cost in bad years. Analysis on rainfall and potential evapotranspiration (PET) from 1961 to 2000 shows that there has been an increasing trend in crop water deficit in the northern part, but a decreasing trend in the southern part of the plain. It remains to be further studied whether this reflects long-term climate change or only a part of the climate variability.
  • Authors:
    • Wei, C. F.
    • Tang, X. H.
    • Wang, Z. F.
    • Luo, Y. J.
    • Gao, M.
  • Source: Pedosphere
  • Volume: 18
  • Issue: 5
  • Year: 2008
  • Summary: The effect of different tillage systems on the size distribution of aggregates and organic carbon distribution and storage in different size aggregates in a Hydragric Anthrosol were studied in a long-term experiment in Chongqing, China. The experiment included three tillage treatments: conventional tillage with rotation of rice and winter fallow (CT-r) system, no-till and ridge culture with rotation of rice and rape (RT-rr) system, and conventional tillage with rotation of rice and rape (CT-rr) system. The results showed that the aggregates 0.02-0.25 mm in diameter accounted for the largest portion in each soil layer under all treatments. Compared with the CT-r system, in the 0-10 cm layer, the amount of aggregates >0.02 mm was larger under the RT-rr system, but smaller under the CT-rr system. In the 0-20 cm layer, the organic carbon content of all fractions of aggregates was the highest under the RT-rr system and lowest under the CT-rr system. The total organic carbon content showed a positive linear relationship with the amount of aggregates with diameter ranging from 0.25 to 2 mm. The storage of organic carbon in all fractions of aggregates under the RT-rr system was higher than that under the CT-r system in the 0-20 cm layer, but in the 0-60 cm soil layer, there was no distinct difference. Under the CT-rr system, the storage of organic carbon in all fractions of aggregates was lower than that under the CT-r system; most of the newly lost organic carbon was from the aggregates 0.002-0.02 and 0.02-0.25 mm in diameter.
  • Authors:
    • Fan, T.
    • Xu, M
    • Song, S.
    • Zhou, G.
    • Ding, L.
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 171
  • Issue: 3
  • Year: 2008
  • Summary: Changes in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for fertilizer treatments were estimated. Mean wheat ( Triticum aestivum L.) yields for the 18 y 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 N and P fertilizers (MNP). Corn ( Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha -1 in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8 kg ha -1 y -1 that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha -1 y -1, similar to the declines of 77.4 kg ha -1 y -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 y -1 which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0-20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil-C sequestration rates ranged from 0.014 t C ha -1 y -1 for the CK to 0.372 t C ha -1 y -1 for the MNP. We found a strong linear relationship ( R2=0.74, p=0.025) between SOC sequestration and cumulative C input, with C conversion-to-SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.
  • Authors:
    • Yu, T. -H.
    • Hayes, D.
    • Tokgoz, S.
    • Fabiosa, J.
    • Elobeid, A.
    • Dong, F.
    • Houghton, R. A.
    • Heimlich, R.
    • Searchinger, T. D.
  • Source: Science
  • Volume: 319
  • Issue: 5867
  • Year: 2008
  • Summary: Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products.
  • Authors:
    • Barfoot, P.
    • Brookes, G.
  • Year: 2008
  • Authors:
    • Zhu, D. W.
    • Jin, Z. Q.
  • Source: Acta Agronomica Sinica
  • Volume: 34
  • Issue: 9
  • Year: 2008
  • Summary: Nine scenarios of climatic change and climatic variability were generated in 19 sites in 3 agroecological zones in northeast China using the WGEN as a tool and based on the output of three general circulation models (GISS, GFDL, and UKMO GCMs), the local current daily weather data from 1961 to 2000 at each site, as well as on the three hypotheses on the increase in climatic variability in future. Four crop models (SOYGRO, CERES-Maize, CERES-Wheat, and CERES-Rice) were selected as the effect models and their parameter modification, validation and sensitivity analyses were carried out using the baseline weather, statistical yield data of the 4 crops and the local typical soil data. Finally, the potential impacts of changes in both climate and its variability on the food production in this regions with a doubling of CO 2 concentration doubled were assessed by running the effect models under both baseline and various (climatic change+climatic change variability) scenarios, and by comparing the outputs simulated. The results showed that the four effect models were available in the studied regions and can be used as a tool in climate impact study. Climate change would be favorable for soyabean and rice production in the region, especially in the northern cold zone and eastern wet zone, but unfavorable for both maize and spring wheat, where the simulated yields particularly maize yield, were significantly reduced under all the scenarios. With increasing of climatic variability, not only the yields were reduced compared with the control, but also the yield stabilities also decreased for the rainfed crops, such as soyabean, maize and spring wheat. However, there was no influence for the irrigated rice.
  • Authors:
    • Zhou, X. L.
    • Liao, M. L.
    • Feng, W. Q.
    • Qin, Y. S.
    • Tu,, S. H.
    • Sun, X. F.
  • Source: Southwest China Journal of Agricultural Sciences
  • Volume: 21
  • Issue: 1
  • Year: 2008
  • Summary: There were considerable differences in amounts of nutrient uptake by the rice cultivar Chuanxiangyou 9838 in different growing periods under no till rape-rice rotation in Sichuan. The rice cultivar absorbed the highest quantity of N in the elongation stage and followed by its maturity and tillering stages. Uptake of P kept a steady increase from seedling stage to its maturity, and the maximal uptake of K occurred during the elongation to earing stages. Based on the nutrient uptake characteristics of the rice cultivar Chuanxiangyou 9838, good nutrient management practices were therefore developed. Application of N should be conducted in early stages and no latter than its elongation. If the soil N supplying ability was not adequate after elongation, an extra N application should be considered to guarantee high yield and quality of the rice. Basal application of P was considered as a proper practice. When the soil as too sandy with low nutrient holding capacity, or too acidic or alkaline with strong ability to fix up P and lose bioavailability, it was better to split P fertilizer to meet requirement at its latter stages. K fertilizers could be applied in early to middle growing stages. If the soil was sandy, it should consider an extra K application after earing stage. It was found that the proper N application rate for the rice cultivar Chuanxiangyou 9838 under no till rape-rice rotation was approximately 165 kg/hm 2 N with a goal of 11 tonnes of rice yield.
  • Authors:
    • Honglei, J.
    • Chenglin, M.
    • Guangyu, L.
    • Dongyan, H.
    • Zhaochen, L.
  • Source: Soil & Tillage Research
  • Volume: 96
  • Issue: 1-2
  • Year: 2007
  • Summary: The combined rototilling-stubble-breaking-planting machine suitable for use in the dry farming area in northern China was developed according to the farming mode of water storage and soil moisture conservation and the performance test and production examination were conducted. The machine uses separated structural design, which can conduct combined rototilling-stubble-breaking-planting operations, and can also be dismantled easily into an independent rototilling-stubble-breaking machine and a planter to conduct the rotilling-stubble-breaking operation or planting operation, or one machine for three purposes. The combined rototilling-stubble-breaking machine is connected with the planter via a compensation-type three-point hitch linkage, ensuring good following performance of the planter and high stability of the combined machine. The rototilling and stubble-breaking performances, the seeding stability, uniformity and evenness between rows of the planter and the performance of the fertilizing unit of the machine were measured. Tests showed that the broken stubble rate was 92%; qualified seed spacing rate: maize 85.80%, soyabean 86.50%; multiples rate: maize 7.60%, soyabean 7.85%; miss rate: maize 6.60%, soyabean 5.63%; the coefficient of variation of the spray capacity of the spray nozzles was 5.94% and the coefficient of variation of the total spray capacity 6.00%. All indexes of the machine reached the requirements stipulated in the related national standards.