19862015
  • Authors:
    • Zheng, Y. K.
    • Yang, G. A.
    • Vasseur, L.
    • You, M. S.
    • Yao, F. L.
  • Source: Crop Protection
  • Volume: 34
  • Year: 2012
  • Summary: The frequent outbreaks of rice planthoppers, especially brown planthopper Nilaparvata lugens (Stal), in the last ten years in China and other Asian countries have caused serious rice ( Oryza sativa L.) yield losses. The key problem is possibly due to biodiversity loss in rice ecosystems. We examined the potential of intercrops of soybean ( Glycine max L.) and corn ( Zea mays L.), both of which are more profitable than rice and mostly planted in levees, to diversify rice ecosystems and enhance insect pest management. We studied the impacts of such intercrops on planthopper populations and their natural enemies. The results showed significantly lower numbers of rice planthoppers in rice fields with intercrops of corn than in rice monocultures and rice fields with intercrops of soybean. Rice fields with corn intercrops had 26-48% fewer planthoppers than rice monoculture. Rice fields with soybean intercrops had lower rice planthopper abundance compared to rice monoculture in 2008 but higher in 2009. However, neither parasitoid nor predator numbers were significantly affected by intercropping. There were no significant differences in directional movements of planthoppers or natural enemies between crop subplots in the different cropping systems. Moreover, movement of planthoppers was very limited. Our study indicated that soybean and corn intercrops do not greatly enhance the ability of natural enemies to suppress planthoppers. However, rice fields with intercrops of corn had lower abundance of planthoppers and this strategy may be useful as part of an integrated pest management strategy for the sustainable rice production.
  • Authors:
    • Hayes, R. M.
    • McClure, M. A.
    • Yin, X. H.
  • Source: Agricultural Sciences
  • Volume: 3
  • Issue: 2
  • Year: 2012
  • Summary: Nitrogen concentration in the ear leaf is a good indicator of corn (Zea mays L.) N nutrition status during late growing season. This study was done to examine the relationship of late-season ear leaf N concentration with early- to mid-season plant height of corn at Milan, TN from 2008 to 2010 using linear, quadratic, square root, logarithmic, and exponential models. Six N rate treatments (0, 62, 123, 185, 247, and 308 kg.N.ha -1) repeated four times were implemented each year in a randomized complete block design under four major cropping systems: corn after corn, corn after soybean [Glycine max (L.) Merr.], corn after cotton [Gossypium hirsutum (L.)], and irrigated corn after soybean. The relationship of ear leaf N concentration determined at the blister growth stage (R 2) with plant height measured at the 6-leaf (V6), 10-leaf (V10), and 12-leaf (V12) growth stages was statistically significant and positive in non-irrigated corn under normal weather conditions. However, the strength of this relationship was weak to moderate with the determination coefficient (R 2) values ranging from 0.21 to 0.51. This relationship was generally improved as the growing season progressed from V6 to V12. Irrigation and abnormal weather seemed to have adverse effects on this relationship. The five regression models performed similarly in the evaluation of this relationship regardless of growth stage, year, and cropping system. Our results suggest that unlike the relationship of corn yield at harvest with plant height measured during early- to mid-season or the relationship of leaf N concentration with plant height when both are measured simultaneously during early- to mid-season, the relationship of late-season ear leaf N concentration with early- to mid-season plant height may not be strong enough to be used to develop algorithms for variable-rate N applications on corn within a field no matter which regression model is used to describe this relationship.
  • Authors:
    • Ziadi, N.
    • Gagnon, B.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 6
  • Year: 2012
  • Summary: Residues from paper and wood mills are a valuable source of nutrients for field crops, but little is known about the effectiveness of repeated applications over many years. A study was initiated at Yamachiche, QC, to assess the effect of continuous applications over 9 yr of combined papermill biosolids (PB), applied alone or with several liming by-products, on grain yield, plant nutrient accumulation, and soil fertility in a loamy soil cropped to grain corn, dry bean, and soybean. The PB treatments (0, 30, and 60 Mg wet ha -1) and liming by-products [calcitic lime (CL), lime mud (LM), wood ash (WA)], and two magnesium residuals, each at 3 Mg wet ha -1 along with (30 Mg PB ha -1) were surface applied annually at post-seeding. In the last 6 yr, the two treatments receiving magnesium residuals were replaced with 90 Mg wet PB ha -1 and mineral N fertilizer (MIN), respectively. Repeated annual applications of LM followed by CL increased soil pH the most (up to 1.4 unit). Crop yields were not significantly affected by treatments in the first 3 yr but subsequent applications of PB at 90 Mg ha -1 increased yields in grain corn (+1.9 Mg ha -1) and dry bean (+0.77 Mg ha -1) relative to the control, while PB with WA increased yield in soybean (+0.85 Mg ha -1). The PB at 30 Mg wet ha -1 with supplemental N (average of 45 kg N ha -1), or at 60 Mg wet ha -1 applied alone, achieved yields comparable with MIN treatment under corn. The PB applications increased soil organic matter and all major soil nutrients except K and Mg. The results of this study indicate that PB and alkaline residuals can be effectively applied to agricultural soils over many years although PB exceeding 60 Mg wet ha -1 yr -1 induce significant nitrate leaching.
  • Authors:
    • Sharma, S. K.
    • Vittal, K. P. R.
    • Kundu, S.
    • Singh, A. K.
    • Lal, R.
    • Venkateswarlu, B.
    • Srinivasarao, C.
    • Sharma, R. A.
    • Jain, M. P.
    • Chary, G. R.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 5
  • Year: 2012
  • Summary: Enrichment of soil organic carbon (SOC) stocks through sequestration of atmospheric CO 2 in agricultural soils is important because of its impacts on improving soil quality and agronomic production, and also for adaptation to and mitigation of climate change. Thus, a 15-yr soil fertility management experiment was conducted in the semi-arid tropical region of central India to evaluate the impact of crop residue C input on soybean ( Glycine max L.)-safflower ( Carthamus tinctorius L.) cropping sequence and SOC sequestration in soils of Vertisolic order (Vertisols). Retention of crop residues of soybean/safflower, and application of farmyard manure (FYM) at 6 Mg (t) ha -1 alone or in combination with 20 kg N and 13 kg P ha -1 supplied through chemical fertilizers or comparatively higher dose of chemical fertilizer (60 kg N and 35 kg P ha -1) either maintained or increased the SOC stock. However, the combination of FYM and chemical fertilizer increased the profile SOC stock (69.9 Mg ha -1), overall SOC build up (37.1%) and also sequestered high amount of SOC (11.9 Mg C ha -1 or 0.79 Mg C ha -1 yr -1) compared with control and chemical fertilizer alone. Higher grain yield (2.10 and 1.49 Mg ha -1 of soybean and safflower, respectively) was obtained through the application of FYM at 6 Mg ha -1+N 20P 13. For every Mg C ha -1 increase in the root zone, there was 0.145 and 0.059 Mg ha -1 increase in grain yield of soybean and safflower, respectively. Stabilization of the SOC stock requires a minimum input of 3.47 Mg C ha -1 yr -1. Application of 40 kg N+26 kg P ha -1 through chemical fertilizer also maintained the SOC stock at the antecedent level based on the SOC stocks in 1992. Therefore, the combined use of organic manure (crop residues and FYM) along with chemical fertilizer is essential to enhancing the SOC sequestration in a soybean-safflower sequence under rainfed conditions on Vertisols in central India.
  • Authors:
    • Lindquist, J. L.
    • Drijber, R. A.
    • Bernards, M. L.
    • Francis, C. A.
    • Wortman, S. E.
  • Source: AGRONOMY JOURNAL
  • Volume: 104
  • Issue: 5
  • Year: 2012
  • Summary: Previous studies have demonstrated benefits of individual cover crop species, but the value of diverse cover crop mixtures has received less attention. The objectives of this research were to determine the effects of spring-sown cover crop mixture diversity and mechanical cover crop termination method on cover crop and/or cash crop productivity, soil moisture and N, and profitability in an organic cropping system. An experiment was conducted between 2009 and 2011 near Mead, NE, where mixtures of two (2CC), four (4CC), six (6CC), and eight (8CC) cover crop species, or a summer annual weed mixture were included in a sunflower-soybean-corn rotation. Cover crops were terminated in late May using a field disk or sweep plow undercutter. Undercutting cover crops increased soil NO 3-N (0-20 cm) by 1.0 and 1.8 mg NO 3-N kg -1 relative to disk incorporation in 2010 and 2011, respectively. Cover crop mixtures often reduced soil moisture (0-8 cm) before main crop planting, though cover crop termination with the undercutter increased soil moisture content by as much as 0.024 cm 3 cm -3 compared to termination with the disk during early main crop growth. Crop yields were not influenced by cover crop mixture, but termination with the undercutter increased corn and soybean yield by as much as 1.40 and 0.88 Mg ha -1, respectively. Despite differences in productivity between spring cover crop mixtures and weed communities, crop yield was not different among these treatments; thus, profitability of the weed mixture-undercutter treatment combination was greatest due to reduced input costs.
  • Authors:
    • Fitt, B. D. L.
    • Smith, P.
    • West, J. S.
    • Carlton, R. R.
  • Source: European Journal of Plant Pathology
  • Volume: 133
  • Issue: 1
  • Year: 2012
  • Summary: Crop disease not only threatens global food security by reducing crop production at a time of growing demand, but also contributes to greenhouse gas (GHG) emissions by reducing efficiency of N fertiliser use and farm operations and by driving land use change. GHG emissions associated with adoption of reduced tillage, organic and integrated systems of field crop production across the UK and selected regions are compared with emissions from conventional arable farming to assess their potential for climate change mitigation. The reduced tillage system demonstrated a modest (< 20%) reduction in emissions in all cases, although in practice it may not be suitable for all soils and it is likely to cause problems with control of diseases spread on crop debris. There were substantial increases in GHG emissions associated with the organic and integrated systems at national level, principally due to soil organic carbon losses from land use change. At a regional level the integrated system shows the potential to deliver significant emission reductions. These results indicate that the conventional crop production system, coupled to reduced tillage cultivation where appropriate, is generally the best for producing high yields to minimise greenhouse gas emissions and contribute to global food security, although there may be scope for use of the integrated system on a regional basis. The control of crop disease will continue to have an essential role in both maintaining productivity and decreasing GHG emissions.
  • Authors:
    • Decock, C.
    • Leakey, A. D. B.
    • Gray, S. B.
    • Venterea, R.
    • Chung, H.
    • Six, J.
  • Source: Soil Biology and Biochemistry
  • Volume: 51
  • Issue: August
  • Year: 2012
  • Summary: In order to predict and mitigate future climate change, it is essential to understand plant-mediated effects of elevated CO2 (eCO(2)) and O-3 (eO(3)) on N-cycling, including N2O emissions. This is of particular interest for agroecosystems. since N-cycling and N2O emissions are responsive to adaptive management. We investigated the interaction of soil moisture content with eCO(2) and eO(3) on potential N2O emissions from SoyFACE during a 28-day laboratory incubation experiment. We also assessed field N2O fluxes during 2 soybean-growing seasons. In addition, we sought to link previously observed changes in soybean growth and production to belowground processes over a longer time scale by analyzing changes in natural abundance stable isotope ratios of soil N (delta N-15). This method relies on the concept that soil delta N-15 can only change when inputs or outputs with an isotope signature different from that of soil N are altered. We found no major effects of eCO(2) and eO(3) on laboratory and field measured N2O emissions. Natural abundance isotope analyses suggested, however, a decrease in belowground allocation of biologically fixed N in combination with decreased total gaseous N loss by eCO(2), resulting in a tighter N cycle in the longer-term. In contrast, the isotope data suggested an increase in belowground allocation of biologically fixed N under eO(3), leading to increased gaseous N loss, most likely in the form of N-2. Given that effects of eCO(2) and eO(3) on N pools and instantaneous transformation rates in surface soil layers of this agroecosystem have been minimal, our results illustrate the importance of evaluating longer-term changes in N turnover rates. We conclude that eCO(2) decelerates whereas eO(3) accelerates N-cycling in the longer-term, but feedback through changed N2O emissions is not occurring in this soybean system. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Dyer,Lisa
    • Oelbermann,Maren
    • Echarte,Laura
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 175
  • Issue: 3
  • Year: 2012
  • Summary: The Argentine Pampa is one of the major global regions for the production of maize (Zea mays L.) and soybean (Glycine max L. [Merr.]), but intense management practices have led to soil degradation and amplified greenhouse-gas (GHG) emissions. This paper presents preliminary data on the effect of maize-soybean intercrops compared with maize and soybean sole crops on the short-term emission rates of CO2 and N2O and its relationship to soil moisture or temperature over two field seasons. Soil organic carbon (SOC) concentrations were significantly greater (p < 0.05) in the maize sole crop and intercrops, whereas soil bulk density was significantly lower in the intercrops. Soil CO2 emission rates were significantly greater in the maize sole crop but did not differ significantly for N2O emissions. Over two field seasons, both trace gases showed a general trend of greater emission rates in the maize sole crop followed by the soybean sole crop and were lowest in the intercrops. Linear regression between soil GHG (CO2 and N2O) emission rates and soil temperature or volumetric soil moisture were not significant except in the 1:2 intercrop where a significant relationship was observed between N2O emissions and soil temperature in the first field season and between N2O and volumetric soil moisture in the second field season. Our results demonstrated that intercropping in the Argentine Pampa may be a more sustainable agroecosystem land-management practice with respect to GHG emissions.
  • Authors:
    • Griffis, T. J.
    • Fassbinder, J. J.
    • Baker, J. M.
  • Source: Agricultural and Forest Meteorology
  • Volume: 153
  • Issue: February
  • Year: 2012
  • Summary: Separation of the photosynthetic (F-P) and respiratory (F-R) fluxes of net CO2 exchange (F-N) remains a necessary step toward understanding the biological and physical controls on carbon cycling between the soil, biomass, and atmosphere. Despite recent advancements in stable carbon isotope partitioning methodology, several potential limitations can cause uncertainty in the partitioned results. Here, we combined an automated chamber system with a tunable diode laser (TDL) to evaluate carbon isotope partitioning under controlled environmental conditions. Experiments were conducted in a climate controlled greenhouse utilizing both soybean (C-3 pathway) and corn (C-4 pathway) treatments. Under these conditions, net exchange of (CO2)-C-13 and (CO2)-C-12 was obtained with an improved signal to noise ratio. Further, the chamber system was used to estimate soil evaporation (E) and plant transpiration (T), allowing for an improved estimate of the total conductance to CO2 (g(c)). This study found that the incorporation of short-term and diel variability in the isotope composition of respiration (delta(R)) caused F-P to nearly double in the corn system while only slightly increasing in the soybean system. Variability in both g(c) and the CO2 bundle sheath leakage factor for C-4 plants (phi) also had a significant influence on F-P. In addition, chamber measurements of F-N and its isotope composition (delta(N)) indicated that post-illumination processes caused a decrease in plant respiration for up to 3 h following light termination. Finally, this study found systematic differences between the isotope and temperature-regression partitioning methods on the diel time scale. Published by Elsevier B.V.
  • Authors:
    • Hastings, A.
    • Sim, S.
    • King, H.
    • Keller, E.
    • Canals, L. M. I.
    • Flynn, H. C.
    • Wang, S.
    • Smith, P.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 5
  • Year: 2012
  • Summary: Many assessments of product carbon footprint (PCF) for agricultural products omit emissions arising from land-use change (LUC). In this study, we developed a framework based on IPCC national greenhouse gas inventory methodologies to assess the impacts of LUC from crop production using oil palm, soybean and oilseed rape as examples. Using ecological zone, climate and soil types fromnatural the top 20 producing countries, calculated emissions for transitions from vegetation to cropland on mineral soils under typical management ranged from -4.5 to 29.4 t CO2-eq ha-1 yr-1 over 20 years for oil palm and 1.247.5 t CO2-eq ha-1 yr-1 over 20 years for soybeans. Oilseed rape showed similar results to soybeans, but with lower maximum values because it is mainly grown in areas with lower C stocks. GHG emissions from other land-use transitions were between 62% and 95% lower than those from natural vegetation for the arable crops, while conversions to oil palm were a sink for C. LUC emissions were considered on a national basis and also expressed per-tonne-of-oil-produced. Weighted global averages indicate that, depending on the land-use transition, oil crop production on newly converted land contributes between -3.1 and 7.0 t CO2-eq t oil production-1 yr-1 for palm oil, 11.950.6 t CO2-eq t oil production-1 yr-1 for soybean oil, and 7.731.4 t CO2-eq t oil production-1 yr-1 for rapeseed oil. Assumptions made about crop and LUC distribution within countries contributed up to 66% error around the global averages for natural vegetation conversions. Uncertainty around biomass and soil C stocks were also examined. Finer resolution data and information (particularly on land management and yield) could improve reliability of the estimates but the framework can be used in all global regions and represents an important step forward for including LUC emissions in PCFs.