19802015
  • Authors:
    • Burr, C.
    • Thorburn, J.
    • Irmak, S.
    • Yang, H. S.
    • Grassini, P.
    • Cassman, K. G.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 1
  • Year: 2011
  • Summary: Appropriate benchmarks for water productivity (WP), defined here as the amount of grain yield produced per unit of water supply, are needed to help identify and diagnose inefficiencies in crop production and water management in irrigated systems. Such analysis is lacking for maize in the Western U.S. Corn Belt where irrigated production represents 58% of total maize output. The objective of this paper was to quantify WP and identify opportunities to increase it in irrigated maize systems of central Nebraska. In the present study, a benchmark for maize WP was (i) developed from relationships between simulated yield and seasonal water supply (stored soil water and sowing-to-maturity rainfall plus irrigation) documented in a previous study; (ii) validated against actual data from crops grown with good management over a wide range of environments and water supply regimes ( n=123); and (iii) used to evaluate WP of farmer's fields in central Nebraska using a 3-y database (2005-2007) that included field-specific values for yield and applied irrigation ( n=777). The database was also used to quantify applied irrigation, irrigation water-use efficiency (IWUE; amount of yield produced per unit of applied irrigation), and the impact of agronomic practices on both parameters. Opportunities to improve irrigation management were evaluated using a maize simulation model in combination with actual weather records and detailed data on soil properties and crop management collected from a subset of fields ( n=123). The linear function derived from the relationship between simulated grain yield and seasonal water supply, namely the mean WP function (slope=19.3 kg ha -1 mm -1; x-intercept=100 mm), proved to be a robust benchmark for maize WP when compared with actual yield and water supply data. Average farmer's WP in central Nebraska was ~73% of the WP derived from the slope of the mean WP function. A substantial number of fields (55% of total) had water supply in excess of that required to achieve yield potential (900 mm). Pivot irrigation (instead of surface irrigation) and conservation tillage in fields under soybean-maize rotation had the greatest IWUE and yield. Applied irrigation was 41 and 20% less under pivot and conservation tillage than under surface irrigation and conventional tillage, respectively. Simulation analysis showed that up to 32% of the annual water volume allocated to irrigated maize in the region could be saved with little yield penalty, by switching current surface systems to pivot, improving irrigation schedules to be more synchronous with crop water requirements and, as a fine-tune option, adopting limited irrigation.
  • Authors:
    • Akmal, M.
    • Hassan, M. F.
    • Habib, G.
    • Ghufranullah
    • Ahmad, S.
  • Source: Pakistan Journal of Botany
  • Volume: 43
  • Issue: 2
  • Year: 2011
  • Summary: The experiment was conducted to compare Pigeon pea (PP) and Sesbania gentia (SG) legumes as catch crop in a permanent cereal based (Wheat-maize) rotation. The residual effect of legumes with or without added fertilizer (N) was studies on subsequent maize crop grown as fodder. The study aimed to evaluate catch crop response as manure or fodder on the following maize. The results showed that SG was higher in crude protein (p
  • Authors:
    • Trethowan, R.
    • Moeller, C.
    • Carrillo-Garcia, A.
    • Verhulst, N.
    • Sayre, K. D.
    • Govaerts, B.
  • Source: Plant and Soil
  • Volume: 340
  • Issue: 1/2
  • Year: 2011
  • Summary: A field experiment was conducted under furrow irrigation on a Vertisol in arid northwestern Mexico, to evaluate sustainable production alternatives for irrigated wheat systems. Treatments included: tillage (conventionally tilled raised beds where new beds are formed after disc ploughing before planting [CTB] and permanent raised beds [PB]) and irrigation regimes (full and reduced). Physical and chemical soil quality was compared among treatments. PB improved soil structure and direct infiltration, increased topsoil K concentrations (0-5 cm; 1.6 cmol kg -1 in PB vs. 1.0-1.1 cmol kg -1 in CTB) and reduced Na concentrations (0-5 cm; 1.3-1.4 cmol kg -1 in PB vs. 1.9-2.2 cmol kg -1 in CTB) compared to CTB. Crop growth dynamics were studied throughout the season with an optical handheld NDVI sensor. Crop growth was initially slower in PB compared to CTB, but this was compensated by increased crop growth in the later stages of the crop cycle which influenced final yield, especially under reduced irrigation. These results were reflected in the final grain yield: in the third year after conversion to PB, no difference in grain yield was found between tillage systems under full irrigation. However, under reduced irrigation the improved soil quality with PB resulted in a 19% and 26% increment in bread and durum wheat grain yields, respectively. As projected climatic scenarios forecast higher evapotranspiration, less reliable rainfall and increased drought, our results indicate that PB could contribute to maintaining and increasing wheat yields in a sustainable way.
  • Authors:
    • Lima, N. R. C. de B.
    • Mendonca, F. C.
    • Santos, P. M.
    • Araujo, L. C. de
  • Source: Revista Brasileira de Zootecnia
  • Volume: 40
  • Issue: 7
  • Year: 2011
  • Summary: The objective of this work was to evaluate the development and productive traits of palisadegrass single cultivated or intercropped with corn, in addition to corn intercropped with pasture, under water deficit at different development stages of the plants. It was used a complete block experimental design with split plots and three replicates. Periods of water deficit were placed in the plots and types of cultivation were placed in the subplots. Irrigation was stopped at germination and initial tillering of palisadegrass and at V4 and V15 stages of corn and returned when soil moisture was 40% of available water capacity. Tiller density and palisadegrass height were evaluated weekly. Dry matter (DM) of fractions of herbage mass as well as leaf area of the plants were evaluated at corn tasseling and when grains reached physiological maturity. Components of corn production were determined in the second sampling. In palisadegrass, water influenced only tillering, which was reduced in the plots in which water defict was forced at the moment of germination or at the beginning of tilering, in both cultivation systems. Plant height and DM production were affected only by cultivation, reducing when intercropped with corn. Evaluated production components did not influence corn grain productivity, which was similar in all treatments (average of 10,145 kg/ha). Palisadegrass plants produce more DM in single cultivation than intercropped with corn. Water deficit during germination and initial tillering reduces tillering of palisadegrass during establishment phase. Water deficit, applied in this trial, does not reduce DM yield in palisadegrass or corn.
  • Authors:
    • Hedtcke, J. L.
    • Stoltenberg, D. E.
    • Posner, J. L.
    • Bernstein, E. R.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 4
  • Year: 2011
  • Summary: A major challenge that organic grain crop growers face is weed management. The use of a rye (Secale cereale L.) cover crop to facilitate no-tillage (NT) organic soybean [Glycine max (L.) Merr.] production may improve weed suppression and increase profitability. We conducted research in 2008 and 2009 to determine the effect of rye management (tilling, crimping, and mowing), soybean planting date (mid-May or early June), and soybean row width (76 or 19 cm), on soybean establishment, soil moisture, weed suppression, soybean yield, and profitability. Soybean establishment did not differ between tilled and NT treatments; and soil moisture measurements showed minimal risk of a drier soil profile in NT rye treatments. Rye mulch treatments effectively suppressed weeds, with 75% less weed biomass than in the tilled treatment by mid-July. However, by this time, NT soybean competed with rye regrowth, were deficient in Cu, and accumulated 22% as much dry matter (DM) and 28% as much N compared to the tilled treatment. Soybean row width and planting date within NT treatments impacted soybean productivity but not profitability, with few differences between mowed and crimped rye. Soybean yield was 24% less in the NT treatments than the tilled treatment, and profitability per hectare was 27% less. However, with fewer labor inputs, profitability per hour in NT rye treatments was 25% greater than in tilled soybean; in addition, predicted soil erosion was nearly 90% less. Although soybean yields were less in NT rye mulch systems, they represent economically viable alternatives for organic producers in the Upper Midwest.
  • Authors:
    • Blaise, D.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: Transgenic Bt cotton hybrids, in India, now constitute more than 90% of the cotton area. Conservation tillage systems such as reduced tillage (RT) improve soil health and crop productivity. Field experiments were conducted to study the response of Bt cotton hybrids to the tillage methods in a split plot design for three years (2005-2006 to 2007-2008) with tillage practices as main plots (conventional tillage {CT}, RT with two inter-row cultivations {RT(1)} and RT with no inter-row cultivation {RT(2)}). In the sub-plot, in situ green manure (GM) was included along with 100 (GM + N(100)), 80 (GM + N(80)) and 60 kg N ha(-1) (GM + N(60)) and were compared to N alone (N(100)). Growth, yield and fibre quality of Bt transgenic cotton hybrid (RCH-2 Bt) were monitored during the study. In all seasons, weed density and biomass were significantly lower in the RT treatments than in the CT treatments. Taller plants with more main stem nodes were produced on the RT plots (63.6-75.8 cm) than on the CT plots (58.1-70.2 cm). Thus, plants of RT treatment retained more bolls (60.8-62.0 m(-2)) than those of the CT treatment (52.4 m(-2)). Averaged over seasons, RT treatment had seed cotton yield (1717-1740 kg ha(-1)) significantly higher than the CT treatment (1489 kg ha(-1)). The treatments N(100), GM + N(100) and GM + N(80) (1687-1734 kg ha(-1)) did not differ and were significantly better than the GM + N(60) (1303 kg ha(-1)). Tillage x GM interaction was significant in two of three years and data combined over years. The RT plots with GM had significantly greater yield than the CT plots. Compared to the CT treatment, the RT plots had significantly greater proportion of water stable aggregates (48.6% vs. 54.4-56.0%) and mean weight diameter (0.47 mm vs. 0.49-0.51 mm). The GM plots had significantly higher WSA and MWD than those without. Further, soil moisture content was greater in the GM mulched plots up to 0.60 m depth compared to without GM treatment (CT + N(100)). Favourable soil physical properties may have contributed to improved seed cotton yield in the RT treatments with GM than in the CT treatment. Fibre quality was not affected by either the tillage systems or GM. This study indicates that Bt transgenic cotton can be grown under RT systems with an in situ legume GM. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Stahlman, P. W.
    • Sistani, K. R.
    • Mikha, M. M.
    • Acosta-Martinez, V.
    • Benjamin, J. G.
    • Vigil, M. F.
    • Erickson, R.
  • Source: Agriculture
  • Volume: 1
  • Issue: 1
  • Year: 2011
  • Summary: Significant amounts of manure are produced in the USA; however, information on the changes in ecosystem services related to soil biogeochemical cycling for agroecosystems supported with organic amendments such as manure is limited. A multi-location field study was initiated in Colorado (CO), Kansas (KS) and Kentucky (KY), USA in loam soils to evaluate the effects of manure and tillage practices on enzyme activities that are key to biogeochemical cycling such as beta-glucosidase (C cycling), alpha-galactosidase (C cycling), beta-glucosaminidase (C and N cycling) and phosphomonoesterases (P cycling). The treatments were as follows: (i) two years of beef manure applications to a fine sandy loam at different rates (control: 0, low: 34 kg N ha -1 and high: 96 kg N ha -1) and tillage practices in CO; (ii) three years of beef manure applications to a silt loam at different rates (0, low: 67 kg N ha -1 and high: 134 kg N ha -1) and tillage practices in KS and; (iii) three years of poultry and dairy manure applications to a silt loam with different tillage practices at the same rate (403 kg N ha -1) in KY. Tillage practices (none vs. conventional) had no effect on the enzyme activities. Principal Component Analyses (PCA) grouped all enzyme activities with the high beef manure application rate after the first year in CO at 0-5 cm. By the second year, the low and high beef manure rates differed in enzyme activities for the KS soil with no difference between the low rate and control in CO. Since the first year of the KY study, acid phosphatase activity was greater in the poultry treated soil compared to dairy or the control; whereas, C cycling enzyme activities were similar in soil treated with dairy or poultry manure. For all studies, PCAs for soil samples from 5-10 cm depth did not reveal treatment separation until the second year, i.e., only high application rate differed from the other treatments. Results of the study indicated significant responses in C and P cycling enzyme activities to manure applications within two years, suggesting potential benefits to soil biogeochemical cycling essential for the productivity of agroecosystems supported with organic fertilizers.
  • Authors:
    • Helgason, B. L.
    • Walley, F. L.
    • Germida, J. J.
  • Source: Applied Soil Ecology
  • Volume: 46
  • Issue: 3
  • Year: 2010
  • Summary: Aggregation is important for soil functioning, providing physical protection of organic matter and microbial inhabitants. Tillage disrupts aggregates, increases wind and water erosion of soils and exposes formerly protected organic matter to decomposition and losses. Microbial biomass and community dynamics in dry-sieved aggregate-size classes from long-term no-till (NT) and conventionally tilled (CT) soils were examined using phospholipid fatty acid analysis (PLFA). Bacterial, fungal, and total biomass were up to 32% greater in NT compared to CT aggregates. Aggregate size also affected microbial biomass, which was highest in the 1-2 mm size class. Arbuscular mycorrhizal fungi (AMF) were particularly affected by tillage disturbance with increases of 40-60% among aggregate-size classes in NT vs. CT, but glomalin related soil protein concentration was not different between tillage treatments or among aggregate-size classes. Bacterial stress biomarkers were higher in CT than NT aggregates but were not significantly correlated with total C, total N or C:N ratio, indicating that the physiological status of bacteria within aggregates was not simply governed by the quantity of available resources. Ordination analysis of PLFA profiles demonstrated a shift in microbial community structure between NT and CT aggregates, correlated with AMF abundance in NT aggregates and increased bacterial stress biomarkers in CT aggregates. Our results demonstrated greater microbial biomass and altered microbial community structure in NT vs. CT aggregates. This work demonstrates that tillage management influences microbial community structure within aggregates and may provide a potential explanation for differences in process rates observed in NT vs. CT soils. Further research into the processes that govern community structure in aggregates from NT and tilled soils is needed to better understand how the interaction of microorganisms with their physical environment affects nutrient turnover and availability.
  • Authors:
    • Lal, R.
    • Jagadamma, S.
  • Source: Biology and Fertility of Soils
  • Volume: 46
  • Issue: 6
  • Year: 2010
  • Summary: Soil organic carbon (SOC) is distributed heterogeneously among different-sized primary particles and aggregates. Further, the SOC associated with different physical fractions respond differently to managements. Therefore, this study was conducted with the objective to quantify the SOC associated with all the three structural levels of SOC (particulate organic matter, soil separates and aggregate-size fractions) as influenced by long-term change in management. The study also aims at reevaluating the concept that the SOC sink capacity of individual size-fractions is limited. Long-term tillage and crop rotation effects on distribution of SOC among fractions were compared with soil from adjacent undisturbed area under native vegetation for the mixed, mesic, Typic Fragiudalf of Wooster, OH. Forty five years of no-till (NT) management resulted in more SOC accumulation in soil surface (0-7.5 cm) than in chisel tillage and plow tillage (PT) treatments. However, PT at this site resulted in a redistribution of SOC from surface to deeper soil layers. The soils under continuous corn accumulated significantly more SOC than those under corn-soybean rotation at 7.5-45 cm depth. Although soil texture was dominated by the silt-sized particles, most of the SOC pool was associated with the clay fraction. Compared to PT, the NT treatment resulted in (i) significantly higher proportion of large macroaggregates (>2,000 m) and (ii) 1.5-2.8 times higher SOC concentrations in all aggregate-size classes. A comparative evaluation using radar graphs indicated that among the physical fractions, the SOC associated with sand and silt fractions quickly changed with a land use conversion from native vegetation to agricultural crops. A key finding of this study is the assessment of SOC sink capacity of individual fractions, which revealed that the clay fraction of agricultural soils continues to accumulate more SOC, albeit at a slower rate, with progressive increase in total SOC concentration. However, the clay fraction of soil under native woodlot showed an indication for SOC saturation. The data presented in this study from all the three structural levels of SOC would be helpful for refining the conceptual pool definitions of the current soil organic matter prediction models.
  • Authors:
    • Lal, R.
    • Ussiri, D. A. N.
    • Trumbore, S. E.
    • Mestelan, S.
    • Jagadamma, S.
  • Source: Biogeochemistry
  • Volume: 98
  • Issue: 1-3
  • Year: 2010
  • Summary: Accurate quantification of different soil organic carbon (SOC) fractions is needed to understand their relative importance in the global C cycle. Among the chemical methods of SOC fractionation, oxidative degradation is considered more promising because of its ability to mimic the natural microbial oxidative processes in soil. This study focuses on detailed understanding of changes in structural chemistry and isotopic signatures of SOC upon different oxidative treatments for assessing the ability of these chemicals to selectively isolate a refractory fraction of SOC. Replicated sampling (to ~1 m depth) of pedons classified as Typic Fragiudalf was conducted under four land uses (woodlot, grassland, no-till and conventional-till continuous corn [ Zea mays L.]) at Wooster, OH. Soil samples (<2 mm) were treated with three oxidizing agents (hydrogen peroxide (H 2O 2), disodium peroxodisulfate (Na 2S 2O 8) and sodium hypochlorite (NaOCl)). Oxidation resistant residues and the bulk soil from A1/Ap1 horizons of each land use were further analyzed by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and accelerator mass spectrometry to determine structural chemistry and 14C activity, respectively. Results indicated that, oxidation with NaOCl removed significantly less SOC compared to Na 2S 2O 8 and H 2O 2. The NMR spectra revealed that NaOCl oxidation preferentially removed lignin-derived compounds at 56 ppm and at 110-160 ppm. On the other hand, the SOC resistant to Na 2S 2O 8 and H 2O 2 oxidation were enriched with alkyl C groups, which dominate in recalcitrant macromolecules. This finding was corroborated by the 14C activity of residual material, which ranged from -542 to -259 per mil for Na 2S 2O 8 resistant SOC and -475 to -182 per mil for H 2O 2 resistant SOC as compared to relatively greater 14C activity of NaOCl resistant residues (-47 to 61 per mil). Additionally, H 2O 2 treatment on soils after light fraction removal was more effective in isolating the oldest ( 14C activity of -725 to -469 per mil) SOC fraction. The Delta 14C signature of SOC removed by different oxidizing agents, calculated by mass balance, was more or less similar irrespective of the difference in labile SOC removal efficiency. This suggests that SOC isolated by many fractionation methods is still a mixture of much younger and older material and therefore it is very important that the labile SOC should be completely removed before measuring the turnover time of stable and refractory pools of SOC.