• Authors:
    • Lal,Rattan
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 4
  • Year: 2015
  • Authors:
    • Northupl,B. K.
    • Rao,S. C.
  • Source: Crop Economics, Production & Management
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Continuous winter wheat ( Triticum aestivum L. em Thell.) is the foundation for most US Southern Great Plains (SGP) agriculture. Inorganic N fertilizers are important to wheat production, but increasing N prices have caused producers to reconsider growing legumes during summer fallow for green N. This study was conducted during 2008 to 2012 to determine the potential for using lablab [ Lablab purpureus (L.) Sweet cv. Rio Verde] to support wheat under conventional and no-till management compared with soybean [ Glycine max (L.) Merr. cv. Laredo] and three inorganic fertilizer treatments (none, 40, and 80 kg N ha -1). Legume seeds were inoculated and sown after wheat harvest each year, grown from June to August, and terminated in early September. Wheat was then sown with or without preplant tillage and grown to maturity. Grain yield, N concentration, and N accumulated in grain were analyzed to define N treatment, tillage system, and year effects. The amount and distribution of precipitation during 2008 to 2012 varied from 53 to 92% and 63 to 160% of the long-term averages for wheat (688 mm) and legume (162 mm) phases. Tillage effects were nonsignificant ( P<0.76), but N treatment * year interactions were significant for grain yield, N concentration, and N accumulated in grain ( P<0.01). The legumes resulted in some single-year increases in grain yield, but the overall yield response was inconsistent. The legume treatments reduced N concentration in wheat grain compared with the unfertilized control. These results show that neither legume was an effective short-term (≤4-yr) N source for systems of continuous wheat production in the SGP.
  • Authors:
    • Panettieri,M.
    • Berns,A. E.
    • Knicker,H.
    • Murillo,J. M.
    • Madejon,E.
  • Source: Soil & Tillage Research
  • Volume: 151
  • Year: 2015
  • Summary: An augment of soil organic matter (SOM) in agricultural lands is mandatory to improve soil quality and fertility and to limit greenhouse gases emissions. A better protection of SOM from degradation is seconded to its inclusion in aggregates and to the formation of organo-mineral interactions with the clay fraction within the soil matrix. Under Mediterranean conditions, conservation agriculture (CA) has been widely related with macro-aggregates formation, SOM protection, and to an improvement of soil fertility and crop yields. The objective of this work was to evaluate the biogeochemical properties of five aggregate-size fractions obtained by dry sieving of a Calcic Fluvisol of an experimental farm managed under three different tillages. Soil aggregates distribution, total organic carbon (TOC), labile carbon pools, and enzymatic activities were measured in 2 different periods of the same agricultural campaign. CPMAS 13C NMR analyses were also performed to elucidate the structure of preserved SOM. The results evidenced seasonal variability in aggregate distribution, labile carbon pools and dehydrogenase activity (DHA), whereas TOC, permanganate oxidizable carbon (POxC), and beta- glucosidase activity demonstrated to be reliable soil quality indices for soil fractions. The NMR analyses showed a better SOM preservation under conservation tillages, due to higher plant litter inputs and/or higher amount of necromass derived compounds if compared with traditional tillage. Particularly interesting are the results of the O 0.5-1 mm fraction, in which different trends were found for beta-Glu and several organic compound classes if compared with the other fractions. Possibly, in this fraction are concentrated most of the products from cellulose depolymerization stabilized by organo-mineral interactions.
  • Authors:
    • Sainju,U. M.
    • Allen,B. A.
    • Caesar-Tonthat,T.
    • Lenssen,A. W.
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Little is known about the long-term management impact on soil C and N contents in the northern Great Plains. We evaluated the 30-yr effect of tillage and cropping sequence combination on dryland crop biomass yield and soil bulk density, soil organic carbon (SOC), soil inorganic carbon (SIC), soil total nitrogen (STN), NH 4-N, and NO 3-N contents at the 0- to 120-cm depth in a Dooley sandy loam (fine loamy, mixed, frigid Typic Argiboroll) in eastern Montana. Treatments were no-till continuous spring wheat ( Triticum aestivum L.) (NTCW), spring till continuous spring wheat (STCW), fall and spring till continuous spring wheat (FSTCW), fall and spring till spring wheat-barley ( Hordeum vulgare L., 1984-1999) followed by spring wheat-pea ( Pisum sativum L., 2000-2013) (FSTW-B/P), and spring till spring wheat-fallow (STW-F, traditional system). Mean annualized crop biomass returned to the soil was 23 to 30% greater in NTCW, STCW, FSTCW, and FSTW-B/P than STW-F. At 0 to 7.5 cm, bulk density was 13 to 21% greater in STW-F, but SOC, SIC, and STN were 12 to 98% greater in STCW than other treatments. Ammonium-N and NO 3-N contents were 25 to 74% greater in FSTCW than other treatments. At other depths, SOC, SIC, STN, NH 4-N and NO 3-N contents varied among treatments. Reduced tillage with increased crop residue returned to the soil increased soil C and N storage in NTCW and STCW, but increased tillage intensity increased mineral N content in FSTCW compared with STW-F. Improved management practices, such as NTCW and STCW, may be adopted to improve dryland soil C and N stocks.
  • Authors:
    • Steenwerth,K. L.
    • Strong,E. B.
    • Greenhut,R. F.
    • Williams,L.
    • Kendall,A.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 20
  • Issue: 9
  • Year: 2015
  • Summary: Purpose: This study assesses life cycle greenhouse gas (GHG) emissions, energy use, and freshwater use in wine grape production across common vineyard management scenarios in two representative growing regions (Napa and Lodi) of the US state of California. California hosts 90 % of US grape growing area, and demand for GHG emissions estimates of crops has increased due to consumer interest and policies such as California’s Global Warming Solutions Act. Methods: The study’s scope includes the annual cycle for wine grape production, beginning at raw material extraction for production of vineyard inputs and ending at delivery of wine grapes to the winery gate, and excludes capital infrastructure. Two hundred forty production scenarios were modeled based on data collected from land owners, vineyard managers, and third-party vineyard management companies. Thirty additional in-person interviews with growers throughout Napa and Lodi were also conducted to identify the diversity of farming practices, site characteristics, and yields (among other factors) across 90 vineyards. These vineyards represent a cross-section of the regional variability in soil, climate, and landscape used for wine grape production. Results and discussion: Energy use and global warming potential (GWP) per metric ton (t) across all 240 production scenarios range between 1669 and 8567 MJ and 87 and 548 kg CO2e. Twelve scenarios were selected for closer inspection to facilitate comparison of the two regions and grower practices. Comparison by region shows energy use, GWP, and water use for typical practices were more than twice as great in Napa (6529 MJ/t, 456 kg CO2e/t, and 265 m3 H2O/t) than Lodi (2759 MJ/t, 203 kg CO2e/t, and 141 m3 H2O/t), but approximately 16 % greater on a per hectare basis. Hand harvest (versus mechanical harvesting) and frost protection processes in Napa contributed to higher values per hectare, and lower yields in Napa account for the even larger difference per metric ton. Hand harvesting and lower yields reflect the higher value of Napa wine grapes. Conclusions: The findings underscore the regional distinctions in wine grape production, which include different management goals, soils, and climate. When vineyards are managed for lower yields, as they are in Napa, energy, water, and GWP will likely be higher on a per mass basis. Strategies to reduce emissions in these regions cannot rely on increasing yields (a common approach), and alternative strategies are required, for example developing high-value co-products. © 2015 Springer-Verlag Berlin Heidelberg
  • Authors:
    • Vanhie,M.
    • Deen,W.
    • Bohner,H.
    • Hooker,D. C.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Many soybean [ Glycine max (Merr.)] growers in northern climates are reverting back to some tillage based on perceptions that increasing corn residues interfere with no-till (NT) soybean performance. Field trials were established in southern Ontario, Canada, to investigate the impact of corn residues on soybean among seven tillage strategies (NT, stalk chop, vertical tillage (VT) twice in the fall, fall and spring VT, fall disc plus spring cultivate, fall disc plus fall cultivate, and fall plowed plus spring cultivate), three corn residue removal treatments (none, intermediate, and nearly complete), and two planters (row-unit and drill). Overall, soybean yields were not different between NT and plowed systems, despite delayed development, and cooler/wetter seedbeds where corn residue was not removed. Shallow tillage after corn harvest did not increase yields from NT alone. Removal of corn residue did not increase soybean yields when averaged across tillage systems. However, NT yield was lowered by 0.36 Mg ha -1 when corn stalks were chopped in the fall, but only in the drill-planted treatments. This result was significant since many farmers have purchased corn combine heads that chop stalks in an attempt to manage residue. Soybean planted with a row-unit planter yielded 0.13 Mg ha -1 higher compared to a drill when averaged across tillage-residue treatments; differences between planters were higher when contending with high amounts of corn residue or an uneven soil surface at planting. Our results show that shallow tillage and/or physically removing corn residue did not improve soybean yield compared to NT alone.
  • Authors:
    • Veenstra,J. J.
    • Burras,C. L.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 4
  • Year: 2015
  • Summary: Despite a large body of scientific research that shows that soils change on relatively short time scales under different management regimes, classical pedological theory states that we should expect these changes to occur only in the surface few centimeters and that they are not of adequate magnitude to suggest fundamental changes in pedon character over short periods of time. In fact, rarely, do the scientists that make these comparisons report on any properties deeper than 30 to 45 cm in the soil profile. With this study, we evaluate soil transformation to a depth of 150 cm after 50 yr of intensive row-crop agricultural land use in a temperate, humid, continental climate (Iowa, United States), by resampling sites that were initially described by the United States soil survey between 1943 and 1963. We find that, through agricultural land use, humans are accelerating soil formation and transformation to a depth of 100 cm or more by accelerating erosion, sedimentation, acidification, and mineral weathering, and degrading soil structure, while deepening dark-colored, organic-matter rich surface horizons, translocating and accumulating organic matter deeper in the soil profile and lowering the water table. Some of these changes can be considered positive improvements, but many of these changes may have negative effects on the soils' future productive capacity. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All rights reserved.
  • Authors:
    • Veum,K. S.
    • Kremer,R. J.
    • Sudduth,K. A.
    • Kitchen,N. R.
    • Lerch,R. N.
    • Baffaut,C.
    • Stott,D. E.
    • Karlen,D. L.
    • Sadler,E. J.
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 4
  • Year: 2015
  • Summary: The Conservation Effects Assessment Project (CEAP). was initiated in 2002 to quantify the potential benefits of conservation management practices throughout the nation. Within the Central Claypan Region of Missouri, the Salt River Basin was selected as a benchmark watershed for soil and water quality assessments. This study focuses on two objectives: (1) assessing soil quality for 15 different annual cropping and perennial vegetation systems typically employed in this region, and (2) evaluating relationships among multiple measured soil quality indicators (SQIs). Management practices included annual versus perennial vegetation, and varying grass species composition (cool-season versus warm-season), tillage intensity (no-till versus mulch-till), biomass removal, rotation phase, crop rotation (corn [Zea mays L.]-soybean [Glycine max L. Merr] versus corn-soybean-wheat [Triticum aestivum L.]) and incorporation of cover crops into the rotation. Soil samples were obtained in 2008 from 0 to 5 cm (0 to 2 in) and 5 to 15 cm (2 to 6 in) depth layers. Ten biological, physical, chemical, and nutrient SQIs were measured and scored using the Soil Management Assessment Framework (SMAF). Across SQIs, biological and physical indicators were the most sensitive to management effects, reflecting significant differences in organic carbon (C), mineralizable nitrogen (N), beta-glucosidase, and bulk density. In the 0 to 5 cm layer, perennial systems demonstrated the greatest SMAF scores, ranging from 93% to 97% of the soil's inherent potential. Scores for annual cropping systems ranged from 78% to 92%: diversified no-till, corn soybean wheat rotation with cover crops (92%) > no-till, corn-soybean rotation without cover crops (88%) > mulch-till corn-soybean rotation without cover crops (84%). Conversely, in the 5 to 15 cm layer, no-till cropping systems scored lower for overall soil function (58% to 61%) than mulch-till systems (65% to 66%). In the 0 to 5 cm layer, biological soil quality under the diversified no-till system with cover crops was 11% greater than under no-till without cover crops, and 20% greater than under mulch-till without cover crops. The effect of rotation phase was primarily reflected in 64% lower mineralizable N following corn relative to soybean. Additionally, soil nutrient function was significantly affected by biomass removal. The results of this study demonstrate that the benefits of conservation management practices extend beyond soil erosion reduction and improved water quality by highlighting the potential for enhanced soil quality, especially biological soil function. In particular, implementing conservation management practices on marginal and degraded soils in the claypan region can enhance long-term sustainability in annual cropping systems and working grasslands through improved soil quality.
  • Authors:
    • Wilson,T. M.
    • McGowen,B.
    • Mullock,J.
    • Arnall,D. B.
    • Warren,J. G.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Fertilizer-induced N 2O-N emissions (the difference between fertilized and unfertilized soils) are estimated to be 0.01 kg N 2O-N kg -1 of applied N. One approach to limiting N 2O-N production in soils is by improving nitrogen use efficiency (NUE) in dryland agricultural systems. However, baseline data on the rate of emissions is needed to determine the potential impact that these efforts might have on N 2O-N concentrations in the atmosphere. A study was established in a long-term continuous winter wheat ( Triticum aestivum L.) fertility experiment in Stillwater, OK, to determine the effects of N rate on N 2O-N emissions from a dryland winter wheat-summer fallow system in the southern Great Plains of the United States to fill this knowledge gap. Cumulative emissions of N 2O-N varied from year to year and were influenced by environment and N rate. Emissions following N fertilizer application were typically highest following N application, as well as toward the end of the summer fallow period, when summer rainfall and temperatures were conducive for N 2O-N production chambers within plots historically receiving 134 kg N ha -1 annually went unfertilized for the 2012-2013 and 2013-2014 crop years and produced N 2O-N emissions equivalent to the 45 and 90 kg N ha -1 rate treatments. Annual cumulative emissions ranged from 0.009 to 0.024 kg N 2O-N kg -1 N applied with an average of 0.015 kg N 2O-N kg -1 N applied, illustrating the variability in N 2O-N emissions.
  • Authors:
    • Dang,Y. P.
    • Moody,P. W.
    • Bell,M. J.
    • Seymour,N. P.
    • Dalal,R. C.
    • Freebairn,D. M.
    • Walker,S. R.
  • Source: Soil & Tillage Research
  • Volume: 152
  • Year: 2015
  • Summary: In semi-arid sub-tropical areas, a number of studies concerning no-till (NT) farming systems have demonstrated advantages in economic, environmental and soil quality aspects over conventional tillage (CT). However, adoption of continuous NT has contributed to the build-up of herbicide resistant weed populations, increased incidence of soil- and stubble-borne diseases, and stratification of nutrients and organic carbon near the soil surface. Some farmers often resort to an occasional strategic tillage (ST) to manage these problems of NT systems. However, farmers who practice strict NT systems are concerned that even one-time tillage may undo positive soil condition benefits of NT farming systems. We reviewed the pros and cons of the use of occasional ST in NT farming systems. Impacts of occasional ST on agronomy, soil and environment are site-specific and depend on many interacting soil, climatic and management conditions. Most studies conducted in North America and Europe suggest that introducing occasional ST in continuous NT farming systems could improve productivity and profitability in the short term; however in the long-term, the impact is negligible or may be negative. The short term impacts immediately following occasional ST on soil and environment include reduced protective cover, soil loss by erosion, increased runoff, loss of C and water, and reduced microbial activity with little or no detrimental impact in the long-term. A potential negative effect immediately following ST would be reduced plant available water which may result in unreliability of crop sowing in variable seasons. The occurrence of rainfall between the ST and sowing or immediately after the sowing is necessary to replenish soil water lost from the seed zone. Timing of ST is likely to be critical and must be balanced with optimising soil water prior to seeding. The impact of occasional ST varies with the tillage implement used; for example, inversion tillage using mouldboard tillage results in greater impacts as compared to chisel or disc. Opportunities for future research on occasional ST with the most commonly used implements such as tine and/or disc in Australia's northern grains-growing region are presented in the context of agronomy, soil and the environment. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.