• Authors:
    • Bert, F. E.
    • Carretero, R.
    • Podesta, G.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: This work presents an assessment of potential advantages of drought tolerance in maize ( Zea mays L.) production. A higher water uptake resulting from an enhanced root exploration at deep soil layers seems to be the most promising mechanism. The potential field-level impacts of this mechanism is assessed in two contrasting agroecological areas of the Argentine Pampas using the CERES-Maize model. The soil root growth factor parameter (SRGF) was manipulated to represent a modified maize hybrid with higher density of deep roots. Enhanced root exploration increased maize transpiration and consequently biomass production and yields. Benefits of the modified hybrid tend to be higher under low water availability conditions (low soil water content at sowing and/or rains during crop cycle). Although higher yield responses to root architecture changes were initially expected in the marginal semiarid area (Pilar), the opposite was observed: the average yield increases were 4.7 and 11.7% for Pilar and Pergamino, respectively. The modified hybrid showed lower yields than the current one in approximately 10% of the simulated situations. There were no yield penalties for the modified hybrid in cropping cycles with high water availability. This work shows strong interactions between root architecture and the environmental conditions in which crops are grown that affect potential field-level benefits. We highlight the need for assessing attributes tied to drought tolerance in the context of agroecological conditions in which plants will be grown to identify which drought-tolerance mechanisms might prove effective under different water-stress conditions.
  • Authors:
    • Ciampitti, I. A.
    • Vyn, T. J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Global food security must address the dual challenges of closing yield gaps (i.e., actual vs. potential yield) while improving environmental sustainability. Nutrient balance is essential for achieving global food security. Historical (in distinct "Eras" from late 1800s to 2012) and geographical (in United States vs. remainder of World) changes in maize ( Zea mays L.) grain yields and plant nutrient content (N, P, and K) were characterized from studies (>150) with known plant densities. At the community scale, greater yield to nutrient content ratios (physiological efficiency, PE) were documented for United States vs. World. The U.S. historical trend displayed increasing gains for community-scale yield and nutrient uptake, except for a recent decline attributed to weather. At the individual-plant scale, geographic PE differences over time were primarily explained by changes in yield, and secondarily by nutrient content changes. Despite wide variation, high-yield maize in both geographies was associated with balanced N/P (5:1) and N/K (1:1) ratios. More scope exists for maize nutrient PE gains in developing regions. Achieving balanced nutrition in optimally integrated soil-crop management cropping systems will facilitate simultaneous realization of high-yield and bio-fortification goals in maize improvement efforts.
  • Authors:
    • Lausen, P.
    • Bottger, F.
    • Herrmann, A.
    • Taube, F.
  • Source: EGF at 50: The future of European grasslands. Proceedings of the 25th General Meeting of the European Grassland Federation, Aberystwyth, Wales, 7-11 September 2014
  • Year: 2014
  • Summary: Changes in soil organic carbon (SOC) stocks of forage cropping systems have a large impact on their greenhouse gas balance. Analysis of a long-term silage maize experiment indicate a positive impact of N fertilization on SOC stocks. Observed differences among treatments were higher than values obtained from a carbon balance based on literature data.
  • Authors:
    • Melillo, J. M.
    • Mutuo, P.
    • Palm, C. A.
    • Hickman, J. E.
    • Tang, J.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 100
  • Issue: 2
  • Year: 2014
  • Summary: National and regional efforts are underway to increase fertilizer use in sub-Saharan Africa, where attaining food security is a perennial challenge and mean fertilizer use in many countries is <10% of nationally recommended rates. Increases in nitrogen (N) inputs will likely cause increased emissions of the greenhouse gas nitrous oxide (N 2O). We established experimental plots with different rates of N applied to maize ( Zea mays) in a field with a history of nutrient additions in western Kenya and measured N 2O fluxes. Fertilizer was applied by hand at 0, 50, 75, 100, and 200 kg N ha -1 in a split application on March 22 and April 20, 2010. Gas sampling was conducted daily during the week following applications, and was otherwise collected weekly or biweekly until June 29, 2010. Cumulative fluxes were highest from the 200 kg N ha -1 treatment, with emissions of 810 g N 2O-N ha -1; fluxes from other treatments ranged from 620 to 710 g N 2O-N ha -1, but with no significant differences among treatments. Emissions of N 2O during the 99-day measurement period represented <0.1% of added fertilizer N for all treatments. Though limited to a single year, these results provide further evidence that African agricultural systems may have N 2O emission factors substantially lower than the global mean.
  • Authors:
    • Nafziger, E. D.
    • Miguez, F. E.
    • Lauer, J. G.
    • Kravchenko, A.
    • Kling, C. L.
    • Gassmann, A. J.
    • Gassman, P. W.
    • Frankenberger, J. R.
    • Fausey, N. R.
    • Cruse, R. M.
    • Bowling, L. C.
    • Bonta, J. V.
    • Basso, B.
    • Arritt, R. W.
    • Anex, R. P.
    • Sawyer, J. E.
    • Mueller, D. S.
    • Castellano, M. J.
    • Lal, R.
    • Herzmann, D.
    • Abendroth, L. J.
    • Helmers, M. J.
    • Kladivko, E. J.
    • Nkongolo, N.
    • O'Neal, M.
    • Owens, L. B.
    • Owens, P. R.
    • Scharf, P.
    • Shipitalo, M. J.
    • Strock, J. S.
    • Villamil, M. B.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: The important questions about agriculture, climate, and sustainability have become increasingly complex and require a coordinated, multifaceted approach for developing new knowledge and understanding. A multistate, transdisciplinary project was begun in 2011 to study the potential for both mitigation and adaptation of corn-based cropping systems to climate variations. The team is measuring the baseline as well as change of the system's carbon (C), nitrogen (N), and water footprints, crop productivity, and pest pressure in response to existing and novel production practices. Nine states and 11 institutions are participating in the project, necessitating a well thought out approach to coordinating field data collection procedures at 35 research sites. In addition, the collected data must be brought together in a way that can be stored and used by persons not originally involved in the data collection, necessitating robust procedures for linking metadata with the data and clearly delineated rules for use and publication of data from the overall project. In order to improve the ability to compare data across sites and begin to make inferences about soil and cropping system responses to climate across the region, detailed research protocols were developed to standardize the types of measurements taken and the specific details such as depth, time, method, numbers of samples, and minimum data set required from each site. This process required significant time, debate, and commitment of all the investigators involved with field data collection and was also informed by the data needed to run the simulation models and life cycle analyses. Although individual research teams are collecting additional measurements beyond those stated in the standardized protocols, the written protocols are used by the team for the base measurements to be compared across the region. A centralized database was constructed to meet the needs of current researchers on this project as well as for future use for data synthesis and modeling for agricultural, ecosystem, and climate sciences.
  • Authors:
    • Lal, R.
    • Kadono, A.
    • Nakajima, T.
    • Kumar, S.
    • Fausey, N.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: Intensive tillage practices and poorly drained soils of the Midwestern United States are one of the prime reasons for increased greenhouse gas (GHG) fluxes from agriculture. The naturally poorly drained soils prevalent in this region require subsurface drainage for improving aeration and reducing GHG fluxes from soils. However, very little research has been conducted on the combination of tillage and drainage impacts on GHG fluxes from poorly drained soils. Thus, the present study was conducted in central Ohio with specific objective to assess the influences of long-term (18-year) no-tillage (NT) and chisel-till (CT) impacts on carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes from the soils in plots managed under drained (D) or nondrained (ND) conditions. The experimental site was established on a poorly drained Crosby silt loam soil in 1994 under corn (Zed mays L.)-corn rotation. Measurements of soil CO2, N2 O, and CH4 fluxes were conducted biweekly during 2011 and 2012 using the static chamber technique. In 2011, the annual CO2-C and N2 O-N from NT were 18% and 83%, respectively, lower compared to CT. Similar trends were observed for 2012. Methane fluxes were highly variable in both years.Tillage and drainage influenced seasonal soil GHG emissions; however, differences were not always significant. In general, plots under NT with subsurface drainage produced lower emissions compared to those under CT. Subsurface drainage lowered the emissions compared to those under ND. Results from this study concluded that subsurface drainage in poorly drained soils with long-term NT practice can be beneficial for the environment by emitting lower GHG fluxes compared to tilled soils with no drainage. However, long-term monitoring of these fluxes under diverse cropping systems under poorly drained soils is needed.
  • Authors:
    • Bursztyn, M.
    • Eiro, F.
    • Parente, I. I.
    • Debortoli, N.
    • Rocha, J. D.
    • Lindoso, D. P.
    • Rodrigues-Filho, S.
  • Source: CLIMATIC CHANGE
  • Volume: 127
  • Issue: 1
  • Year: 2014
  • Summary: Smallholder farming is among the most vulnerable sectors due to its great social and economic sensitivity. Despite future climate change, current climate variability is already an issue of concern that justifies adaptation efforts. In Brazil, the Semi-Arid Region is a climate hotspot, well known for both historic socioeconomic setbacks, and agriculture failures caused by dry spells and severe droughts. In 2010, the Brazilian government enacted the National Policy on Climate Change, which states as one of its key goals the identification of vulnerabilities and the adoption of adequate measures of adaptation to climate change. The improvement of vulnerability assessment tools is a response to the growing demand of decision makers for regular information and indicators with high spatial and temporal resolution. This article aims at undertaking a comparative assessment of smallholder farming's vulnerability to droughts. An integrated assessment system has been developed and applied to seven municipalities located in the Brazilian Semi-Arid Region (within the State of Ceara). Results show regional vulnerability contrasts driven by institutional and socioeconomic factors, beyond climatic stressors.
  • Authors:
    • Duan, W. X.
    • Cheng, D. J.
    • Bu, Q. G.
    • Li, Zizhong
    • Lu, X. J.
    • Sun, Z. H.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: The Corn Belt of Northeast China is the most important corn production area in China, accounting for 30% of the total corn production. However, seasonal drought conditions limit local corn production. Field experiments were conducted in 2011 and 2012 in Lishu county (Jilin Province, China) to study the effects of ridge and furrow rainfall harvesting and mulching on corn yields, evapotranspiration (ET), and water use efficiency (WUE) in black and aeolian sandy soils. The treatments included flat planting bed (FB), plastic-mulched ridges with bare furrows (RFB), and plastic-mulched ridges with straw-mulched furrows (RFM). For both soil types, the RFB and RFM treatments improved soil water conditions in the root zone. However, adding straw mulch did not consistently improve soil water content. In the black soil, the RFB treatment did not affect crop yield but increased WUE by 13% relative to the FB treatment in 2011. Furthermore, yield and WUE decreased by 30 and 24%, respectively, in 2012. In the aeolian sandy soil, the RFB treatment increased yield and WUE by 26 and 25%, respectively, relative to the FB treatment in 2011. However, the RFB treatment had no effect on yield or WUE in 2012. For both soil types, the RFM treatment did not significantly affect yield or WUE relative to the RFB treatment during 2011 or 2012. Therefore, the RFB treatment should only be used in aeolian sandy soils to achieve higher corn yields and WUEs and not be recommended for black soils when the soil water is sufficient.
  • Authors:
    • Giuliante, A.
    • Donoso, L.
    • Pérez, T.
    • Marquina, S.
    • Rasse, R.
    • Herrera, F.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Year: 2014
  • Summary: The largest share of Latin American and Caribbean (LAC) anthropogenic greenhouse gases is derived from land use changes as well as forestry and agriculture, representing up to 67 % of the relative contribution from all sources. However, in spite of the rapid expansion of LAC tropical agriculture, little is known about its impact on atmospheric trace gases emissions, such as nitrogen oxides (NOx), nitrous oxide (N2O) and carbon dioxide (CO2), which are produced in soils by microbial processes and also accelerated in tropical climates. This information is crucial for assessing mitigation strategies linked to agricultural practices to satisfy food demands for the region’s future. We measured NO, N2O and CO2 soil emissions along with soil variables from corn fields under tillage (T) and no-tillage (NT) agriculture at two of the largest cereal-producing regions in Venezuela during the crop-growing season. We found statistically significant positive correlations between the logarithms of nitrogen gas emissions and soil inorganic nitrogen concentrations, soil water and clay contents. Average emissions of NO and CO2 were larger in T than NT sites, while N2O fluxes showed the opposite. CO2 emissions from T were 1.6 as much as those found in NT, whereas N2O was 0.5 of that found in NT. These results imply that NT practices more effectively mitigate climate change from these monoculture systems mainly because of CO2 emission reduction. We suggest then that agricultural mitigation actions for tropical monoculture systems should aim for the enhancement of NT management practices along with N fertilization rate reduction to compensate for the larger N2O emissions.
  • Authors:
    • Davis, J. G.
    • Reich, R.
    • Longchamps, L.
    • Khosla, R.
    • Moshia, M. E.
    • Westfall, D. G.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Precision manure management is a relatively new concept that merges the best agronomic and manure management practices along with precision agricultural techniques, such as site-specific management zones (MZs), for agricultural productivity and environmental quality. The objective of the study was to assess the influence and compare the economic efficiency of variable-rate applications of animal manure on grain yield in maize ( Zea mays L.) fields across MZs in limited irrigation cropping systems. The study was conducted on furrow-irrigated maize fields in northeastern Colorado, USA. Fields were classified into low, medium, and high yielding MZs, based on soil color, elevation, and yield history. Experimental strips were 4.5 m wide and 540 m long spanning across all MZs with manure and N fertilizer management strategies nested within MZs. Variable-rate manure applications of 22, 44, and 67 Mg ha -1 were considered for variable yield goal (VYG) and constant yield goal (CYG) manure management strategies. The results of this study indicates that maize grain yield was significantly different across MZs a majority of times, however, not always consistent with the MZ productivity level. For instance, the low MZ showed a significantly ( P≤0.05) higher grain yield under a CYG manure management strategy. The enterprise budget analysis indicated that application of animal manure alone was economically inefficient for maize grain production. The study suggests that variable-rates of manure can be used in conjunction with synthetic N fertilizer to ensure that crop N requirements are met at early growth stages of maize.