• Authors:
    • Lobell, D.
    • Schlenker, W.
    • Roberts, M.
    • Urban, D.
  • Source: Journal
  • Volume: 130
  • Issue: 2
  • Year: 2015
  • Summary: Short durations of very high spring soil moisture can influence crop yields in many ways, including delaying planting and damaging young crops. The central United States has seen a significant upward trend in the frequency and intensity of extreme precipitation in the 20th century, potentially leading to more frequent occurrences of saturated or nearly saturated fields during the planting season, yet the impacts of these changes on crop yields are not known. Here we investigate the yield response to excess spring moisture for both maize and soybean in the U.S. states of Illinois, Iowa, and Indiana, and the impacts of historical trends for 1950-2011. We find that simple measures of extreme spring soil moisture, derived from fine-scale daily moisture data from the Variable Infiltration Capacity (VIC) hydrologic model, lead to significant improvements in statistical models of yields for both crops. Individual counties experience up to 10 % loss in years with extremely wet springs. However, losses due to historical trends in excess spring moisture measures have generally been small, with 1-3 % yield loss over the 62 year study period.
  • Authors:
    • Coulter, J. A.
    • Venterea, R. T.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Modification of N fertilizer application timing within the growing season has the potential to reduce soil nitrous oxide (N 2O) emissions but limited data are available to assess its effects. We compared cumulative growing season nitrous oxide emissions (cN 2O) following urea applied to corn ( Zea mays L.) in a single application (SA) at planting or in three split applications (SpA) over the growing season. For both SA and SpA, granular urea was broadcast and incorporated at six fertilizer N rates in the corn phase of a corn-soybean [ Glycine max (L.) Merr.] rotation and in a continuous corn system over two growing seasons. Daily N 2O flux was measured using chambers on 35 dates in 2012 and 40 dates in 2013 and soil nitrate-N concentration was measured weekly. Split application did not affect grain yield and did not reduce cN 2O. Across N rates and rotations, cN 2O was 55% greater with SpA compared with SA in 2012. Increased cN 2O with SpA in 2012 likely resulted from a prolonged dry period before the second split application followed by large rainfall events following the third split application. Across years and rotations, SpA increased cN 2O by 57% compared with SA when the maximum N rate was applied. Exponential relationships between cN 2O and fertilizer N rate explained 62 to 74% of the variance in area-based cN 2O and 54% of the variance in yield-based cN 2O. Applying urea to coincide with periods of high crop N demand does not necessarily reduce and may increase N 2O emissions.
  • 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:
    • Grosso, S. J.
    • Spatari, S.
    • Pourhashem, G.
    • Mitchell, J. G.
    • Adler, P. R.
    • Parton, W. J.
  • Source: Research Article
  • Volume: 25
  • Issue: 4
  • Year: 2015
  • Summary: Crop residues are potentially significant sources of feedstock for biofuel production in the United States. However, there are concerns with maintaining the environmental functions of these residues while also serving as a feedstock for biofuel production. Maintaining soil organic carbon (SOC) along with its functional benefits is considered a greater constraint than maintaining soil erosion losses to an acceptable level. We used the biogeochemical model DayCent to evaluate the effect of residue removal, corn stover, and wheat and barley straw in three diverse locations in the USA. We evaluated residue removal with and without N replacement, along with application of a high-lignin fermentation byproduct (HLFB), the residue by-product comprised of lignin and small quantities of nutrients from cellulosic ethanol production. SOC always decreased with residue harvest, but the decrease was greater in colder climates when expressed on a life cycle basis. The effect of residue harvest on soil N 2O emissions varied with N addition and climate. With N addition, N 2O emissions always increased, but the increase was greater in colder climates. Without N addition, N 2O emissions increased in Iowa, but decreased in Maryland and North Carolina with crop residue harvest. Although SOC was lower with residue harvest when HLFB was used for power production instead of being applied to land, the avoidance of fossil fuel emissions to the atmosphere by utilizing the cellulose and hemicellulose fractions of crop residue to produce ethanol (offsets) reduced the overall greenhouse gas (GHG) emissions because most of this residue carbon would normally be lost during microbial respiration. Losses of SOC and reduced N mineralization could both be mitigated with the application of HLFB to the land. Therefore, by returning the high-lignin fraction of crop residue to the land after production of ethanol at the biorefinery, soil carbon levels could be maintained along with the functional benefit of increased mineralized N, and more GHG emissions could be offset compared to leaving the crop residues on the land.
  • Authors:
    • Congreves, K. A.
    • Eerd, L. L.
  • Source: Journal Article
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Vegetables are important horticultural commodities with high farm gate values and nutritional quality. For many vegetables, growers apply large amounts of N fertilizer (>200 kg N ha-1) to increase yield and profits, but such high N fertilizer applications can pose a significant threat for N loss and environmental contamination via denitrification, volatilization, leaching, runoff, and erosion. Nitrogen losses can reduce air and water quality by contributing to greenhouse gas emissions, ground-level ozone and particulate matter production, ground and surface water contamination, and eutrophication. The processes governing N loss include a complex of biological, physical, and chemical factors, which are impacted by management practices, climatic conditions and soil properties. Therefore, we reviewed and evaluated various management practices for minimizing N loss in N-intensive vegetable production within a temperate climate. Most soil nutrient management practices have focused on reducing N loss throughout the growing season, but the risk for N loss is very high after harvesting vegetables with low N harvest indices, low C:N ratios, and high quantities of N in crop residues, such as most Brassicaoleracea L. crops. Amending soil with organic C material may present a novel strategy for reducing N losses after harvest by 37 %, compared to the typical practice of incorporating N-rich vegetable crop residues. Research must focus on testing new and innovative methods of minimizing post-harvest N loss in intensive horticulture. © 2015 Springer Science+Business Media Dordrecht