• Authors:
    • Zheng, X.
    • Wang, K.
    • Yao, Z.
    • Liu, C.
  • Source: Science Article
  • Volume: 203
  • Year: 2015
  • Summary: Global nitrogen fertilizer consumption is expected to continue to increase. To explore effective mitigation strategies, a deeper understanding of the responses of nitrogen use efficiency, nitric oxide (NO) emission and the NO direct emission factor (EF d) to increasing fertilization rates is needed. A gradient of fertilization rates (0, 135, 270, 430, 650 and 850 kg N ha -1 yr -1 in the form of urea, hereafter referred to as N0, N135, N270, N430, N650 and N850, respectively) was used to fully represent the nitrogen application levels in the wheat-maize rotational cropping system that has been widely adopted in China. The annual NO emissions ranged from 0.430.04 (N0) to 2.640.35 kg N ha -1 yr -1 (N850) and linearly increased with increasing fertilization rates ( P<0.01). The high pH and low carbon availability in the calcareous soil limited NO production; thus, low EF d values (0.26-0.36%) were observed. The partial factor productivity of applied nitrogen (PFP N) rapidly decreased with increasing fertilization rates; the relationship could be characterized by a rectangular hyperbolic function ( P<0.01). The expected trade-off between EF d and PFP N was not observed. The on-farm PFP N was only 333 kg grain kg -1 N (N430), highlighting the necessity of optimizing current management strategies. Based on a review of previous studies, a comprehensive optimized management strategy is recommended to obtain the maximum benefits for multiple goals of a wheat-maize cropping system. However, consecutive field observations and model studies are still needed to validate the long-term effects of this management strategy.
  • Authors:
    • Bu, Q.
    • Sun, Z.
    • Li, Z.
    • Lu X.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Straw mulching is used widely to improve soil fertility in the black soil region of northeastern China, but there have been few evaluations of its effects on soil water content, N use by crops, and crop growth. Field experiments were conducted during two growing seasons in Jilin Province, to study the effects of straw mulching on maize yield, evapotranspiration (ET), water use efficiency (WUE), and nitrogen use efficiency (NUE) under rainfed conditions. Measurements were conducted in a treatment with maize straw mulch on the soil surface (SM) and a control treatment with no mulch (NM). The SM treatment caused a significant decline of soil temperature and increase of soil moisture in the early growing season, compared to the NM treatment. However, the use of mulching reduced maize yields by 18% in 2011 and 26% in 2012. It also decreased WUE by 16% in 2011 and 21% in 2012, and decreased NUE by 27% in 2012, though it had no effect on total ET. Therefore, the use of mulch is not recommended as an approach for improving water and N use and maize yields, in the semi-humid black soil region of northeastern China, when the water content of soil is sufficient for maize growth.
  • Authors:
    • Yu, Z.
    • Zhang, Y.
    • Shi, Y.
    • Guo, Z.
    • Wang, H.
  • Source: Article
  • Volume: 153
  • Year: 2015
  • Summary: Although the effects of tillage practices on soil properties and root growth is well studied, how they affect nitrogen accumulation and translocation in wheat in dryland regions is poorly understood. Here, the impact of different tillage practices, namely, strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R), and rotary tillage after subsoiling (RS), on nitrogen accumulation and translocation, grain yield, and economic benefit in wheat and soil nitrate-nitrogen leaching in drylands was studied over three wheat growing seasons from 2009 to 2012. The results showed that compared with R, nitrogen accumulation amount under SRS increased by 36.8% from jointing to maturity in 2009-2011 and by 12.9 and 16.4% from sowing to maturity in 2009-2010 and 2010-2011, respectively. Post-anthesis nitrogen accumulation, its contribution rate to grain and nitrogen accumulation in grains at maturity under SRS were 48.3, 31.3 and 12.7% higher, respectively, compared to that under R in 2009-2010. On the other hand, nitrate-nitrogen accumulation under SRS in 0-60cm soil layers was lower in comparison to that under SR and R, which suggested that SRS promoted absorption of nitrate-nitrogen in soil layers by wheat. However, no significant difference in nitrate-nitrogen accumulation in the 60-200cm soil layers was observed between SR and R. Average grain yield, nitrogen production efficiency and economic benefit were all the highest under SRS at 598.78gm-2, 39.9kgkg-1 and 8350.8 RMB¥ha-1, respectively, over the study period. Therefore, we propose that SRS is the optimal tillage practice for wheat production in this region. © 2015 Elsevier B.V.
  • Authors:
    • Chang, J.
    • Cheng, J.
    • Peng, C.
    • Yang, G.
    • Ren, Y.
    • Gu, B.
    • Liu, D.
    • Wang, Y.
    • Ge, Y.
    • Wu, X.
  • Source: Journal of Cleaner Production
  • Volume: 95
  • Year: 2015
  • Summary: It is still controversial as to whether intensive agriculture increases or decreases carbon emissions compared to conventional farming. Carbon flux changes induced by the conversion of agricultural practices in different climatic regions have long been a scientific focus. As an intensive cultivation practice, vegetable cultivation within plastic greenhouses (PGVC) has been reported to reduce net carbon emissions following the conversion from conventional vegetable cultivation (CVC). However, it remains uncertain to what degree the carbon flux changes following the conversion in different climatic regions. Based on 637 paired soil data points and 189 vegetable data points from five major climatic regions in China, we used a full carbon cycle analysis to estimate the carbon flux changes when converting from CVC to PGVC. Results showed that the conversion reduced net carbon emissions in four climatic regions (middle temperate, warm temperate, south subtropical and north subtropical regions) but increased net carbon emissions in the Tibet Plateau region. This regional variation was attributable to the differences between soil carbon sequestration and fossil fuel emissions. The highest reduction (1.46 Mg C ha(-1) yr(-1)) occurred in the middle temperate region while the Tibet Plateau region acted as a net carbon source (-0.24 Mg C ha(-1) yr(-1)). This suggests that the conversion can increase carbon benefits within the four climatic regions. PGVC in these regions could be considered as a promising option for carbon-smart intensive agriculture and would be worth expanding in countries with similar weather conditions, to mitigate carbon emissions. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Yang, Q.
    • Su, Y.
    • Yang, R.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Knowledge of the effect of long-term fertilizer application on arable lands reclaimed from the desert in arid regions is limited. In this study, we used data obtained from a 7-yr field experiment to determine the effect of different fertilizer application strategies on crop yields and soil nutrient status in a desert oasis of northwest China. Our results showed that integrated fertilizer application (IFA) treatments produced average maize ( Zea mays L.) and soybean [ Glycine max (L.) Merr.] yields 10.3 and 13.3% greater than those under chemical fertilizer application (CFA) treatments and 56.0 and 7.3% greater than those under organic manure application (OMA) treatment. With one exception for a K treatment, the average grain yield during the 7 yr of the study tended to increase with increased nutrient rates, and reached the maximum value at a 281 kg ha -1 N, 171 kg ha -1 P 2O 5, and 544 kg ha -1 K 2O input level. At the end of the study, soil organic matter (SOM) and total N were the highest in the soil treated with OMA, followed by those treated with IFA and then CFA. High CFA rates increased soil phosphorus levels. The crop yield values linearly increased with the increase in SOM, total N, available N, and available K. Our findings suggested that in the desert oasis ecosystem, an IFA system increased both crop yields and soil nutrients.
  • Authors:
    • YaJun, G.
    • QunHu, C.
    • PengWei, Y.
    • ChangWei, Y.
    • Zheng, W.
    • Na, Z.
    • DaBin, Z.
    • WeiDong, C.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Scant rainfall and poor soil fertility are the two major obstructions to crop production on the Loess Plateau. To improve crop productivity and to reduce N fertilizer rates, a 4-yr field experiment was conducted to investigate the effects of leguminous green manure (GM) and N fertilizer on winter wheat ( Triticum aestivum L.) growth, yield, and economics on the Loess Plateau. Following a split-plot design, the main treatments included three legume species: Huai bean ( Glycine ussuriensis Regel et Maack.), soybean [ G. max (L.) Merr.], mung bean ( Phaseolus radiatus L.), and summer fallow (as control treatment [CK]); The subtreatments included four N fertilizer rates that were applied to the wheat. Leguminous GM apparently improved wheat growth, productivity, and nutrient uptake compared to bare fallow, especially during a wet year. At least 2 yr and abundant rainfall are required for bettering the GM approaches. Incorporation of GM for 4 yrs could effectively reduce the N fertilizer rate for wheat by 33% (54 kg N ha -1), with even more potential during a wet year. High expenditures for field management and variable weather patterns led to few direct economic benefits of GM approaches. Huai bean is a more profitable legume species to be used as GM crops. The cultivation of leguminous GM during summer is a better option than bare fallow for sustaining wheat productivity, and decreasing the required N fertilizer rates not only on the Loess Plateau of China but also in the other similar dryland regions around the world.
  • Authors:
    • Wu, Z.
    • Gong, P.
    • Yang, L.
    • Burger, M.
    • Chen, W,
    • Zhang, L.
  • Source: Research Article
  • Volume: 10
  • Issue: 2
  • Year: 2015
  • Summary: In order to discover the advantages and disadvantages of different fertilization regimes and identify the best management practice of fertilization in greenhouse fields, soil enzyme activities involved in carbon (C) transformations, soil chemical characteristics, and crop yields were monitored after long-term (20-year) fertilization regimes, including no fertilizer (CK), 300 kg N ha -1 and 600 kg N ha -1 as urea (N1 and N2), 75 Mg ha -1 horse manure compost (M), and M with either 300 or 600 kg N ha -1 urea (MN1 and MN2). Compared with CK, fertilization increased crop yields by 31% (N2) to 69% (MN1). However, compared with CK, inorganic fertilization (especially N2) also caused soil acidification and salinization. In the N2 treatment, soil total organic carbon (TOC) decreased from 14.10.27 g kg-1 at the beginning of the long-term experiment in 1988 to 12.60.11 g kg-1 (P<0.05). Compared to CK, N1 and N2 exhibited higher soil alpha-galactosidase and beta-galactosidase activities, but lower soil alpha-glucosidase and beta-glucosidase activities ( P<0.05), indicating that inorganic fertilization had different impacts on these C transformation enzymes. Compared with CK, the M, MN1 and MN2 treatments exhibited higher enzyme activities, soil TOC, total nitrogen, dissolved organic C, and microbial biomass C and N. The fertilization regime of the MN1 treatment was identified as optimal because it produced the highest yields and increased soil quality, ensuring sustainability. The results suggest that inorganic fertilizer alone, especially in high amounts, in greenhouse fields is detrimental to soil quality.
  • Authors:
    • Ren, X.
    • Han, Q.
    • Jia, Z.
    • Wang, K.
    • Li, Y.
    • Wei, T.
    • Zhang, P.
  • Source: Article
  • Volume: 153
  • Year: 2015
  • Summary: The soil degradation caused by conventional tillage in rain-fed areas of northwest China is known to reduce crop yields because of major losses of soil organic carbon and nutrients. To evaluate the effects of straw incorporation on soil organic carbon (SOC) and total nitrogen (STN) sequestration capacity in loessial soil, we investigated the effects of straw incorporation on SOC, STN and crop yield in semiarid areas of southern Ningxia for a 4-year period (2007-2010). Four treatments were tested: (i) no straw incorporation (NA); (ii) incorporation of maize straw at a low rate of 4.5Mgha-1yr-1 (LA); (iii) incorporation of maize straw at a medium rate of 9.0Mgha-1yr-1 (MA); and (iv) incorporation of maize straw at a high rate of 13.5Mgha-1yr-1 (HA). In the final year (2010), the results showed that the mean soil bulk density in the 0-60cm depth had decreased with high, middle, and low straw incorporation rate treatment compared with no straw incorporation treatment (NA) by 3.7% (P low straw incorporation rate treatment > no straw incorporation treatment. The mean soil C:N ratio was significantly higher with straw incorporation, i.e., 6.9% higher than no straw incorporation treatment. Straw incorporation significantly (P<0.05) increased the stratification ratio of SOC, STN, and soil C:N ratio from the surface (0-10cm) to all depths compared with NA, i.e., the stratification ratio of SOC at the 0-10:20-40cm depth increased with HA, MA and LA by 11.3% (P<0.05), 10.7% (P<0.05), and 4.4%, respectively, compared with no straw incorporation treatment (NA). © 2015.
  • Authors:
    • Miao,Shujie
    • Qiao,Yunfa
    • Zhang,Futao
  • Source: Polish Journal of Environmental Science
  • Volume: 24
  • Issue: 3
  • Year: 2015
  • Summary: In converting cropland to grassland and forest, more carbon is sequestered in grassland soil and forest biomass, but the mitigation of global warming potential (GWP) is not clear. In this study, we use the lon-gterm conversion from cropland to grassland (28 y) and forest (14 y) to comprehensively assess the impact on GWP of soil carbon (C), nitrogen (N), CO2 and N2O emissions. The results showed that compared to the original cropland, conversion to grassland increased soil C content by 51.1%, soil N content by 28.4%, soil C stock (SCS) by four times, CO2 emission by 17%, and N2O emission by 40%; soil N stock (SNS) decreased by half. The corresponding values after afforestation were 7.2%, 5.2%, three times, 3%, -80%, and half, respectively. Overall GWP in the cropland system was calculated using the fuel used for farming production, the change in soil C, and N2O emissions. Due to large C sequestration, the GWP of conversion to grassland (-1667 kg CO2-C equivalent ha(-1).y(-1)) and forest (-324 kg CO2-C equivalent ha(-1).y(-1)) were significantly lower than the cropland system (755 kg CO2-C equivalent ha(-1).y(-1)). The relationship between GWP and greenhouse gas, between GWP and the change of total C and N, suggest that in rain-fed agricultural systems in northeast China, the conversion from cropland to grassland and forest can mitigate GWP through changing CO2 and N2O emissions.
  • Authors:
    • Kibue,Grace Wanjiru
    • Pan,Genxing
    • Zheng,Jufeng
    • Li Zhengdong
    • Mao,Li
  • Source: Environment, Development and Sustainability
  • Volume: 17
  • Issue: 3
  • Year: 2015
  • Summary: Agricultural production is a complex interaction between human and natural environment, making agriculture both significantly responsible and vulnerable to climate change. China, whose socioeconomy is fundamentally dependent on agriculture, is already experiencing climate-change-related issues that threaten food security and sustainable development. Climate change mitigation and adaptation are of great concern to ensure food security for the growing population and improve the livelihoods of poor smallholder producers. A questionnaire survey was conducted in Henan Province, China to assess agronomic practices of smallholder farmers, adaptation strategies and how climate change awareness and perceptions influence the farmers' choice of agronomic practices. The results showed that the vast majority of farmers owned < 10 Chinese Mu (0.7 ha) and nearly all farmers' relied on intensive use of chemical fertilizers and pesticides to increase yield at the detriment of environment. However, farmers who were aware of climate change had adopted agronomic practices that reduce impacts of climate change. Information about climate change, lack of incentives, lack of credit facilities and small farm sizes were major hindrance to adaptation and adoption of farming practices that can reduce impacts of climate change. This study recommends that research findings should be disseminated to farmers in timely and appropriate ways. The central government should formulate policies to include subsidies and incentives for farmers to motivate adoption of eco-friendly agronomic practices.