• Authors:
    • Skaggs, K. E.
    • Irmak, S.
  • Source: Transactions of the ASABE
  • Volume: 54
  • Issue: 3
  • Year: 2011
  • Summary: The lack of knowledge and data on the driving forces of nighttime (nocturnal) evapotranspiration (ET) for various vegetation surfaces under different climatic and management conditions led this study to investigate the magnitude of nighttime ET (ET night) and its interactions with other nighttime surface energy fluxes, i.e., soil heat flux (G night), sensible heat flux (H night), and net radiation (R n_night), and microclimatic variables, i.e., wind speed at 3 m (u 3_night), vapor pressure deficit (VPD night), and air temperature (T night). Soybean [( Glycine max (L.) Merr.)] canopies under two different irrigation methods in subsurface drip- and center-pivot irrigated (SDI and CP) fields in south central Nebraska were studied. Hourly energy flux and meteorological data from the SDI field for the 2007 and 2008 seasons and from the CP field for 2008 were analyzed. The study period was divided into five sub-periods based on plant and canopy development to evaluate nighttime energy balances and driving forces at various plant growth and development stages. The five sub-periods are: pre-planting (from mid-March to plant emergence, EM), early season (from emergence to full canopy cover, leaf area index, LAI
  • Authors:
    • Armstrong, S. D.
    • Hernandez-Ramirez, G.
    • Smith, D. R.
    • Bucholtz, D. L.
    • Stott, D. E.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 3
  • Year: 2011
  • Summary: Recent efforts have attempted to establish emission estimates for greenhouse gas (GHGs) from agricultural soils in the United States. This research project was conducted to assess the influence of cropping system management on non-CO(2) GHG emissions from an eastern Corn Belt Alfisol. Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation plots were established, as were plots in continuous management of native grasses or sorghum-sudan-grass [Sorghum bicolor (L.) Moench nothossp. drummondii (Steud.) de Wet ex Davidse]. Greenhouse gas fluxes were monitored throughout each growing season from 2004 through 2007. Fluxes of N(2)O were significantly correlated with soil temperature (P
  • Authors:
    • Tadesse, T.
    • Narumalani, S.
    • Wardlow, B. D.
    • Swain, S.
    • Callahan, K.
  • Source: GIScience & Remote Sensing
  • Volume: 48
  • Issue: 3
  • Year: 2011
  • Summary: Eight-day composite Terra-MODIS cumulative LST and NDVI timeseries data were used to analyze the responses of crop and grassland cover types to drought in Nebraska. Four hundred ninety 1 km pixels that included irrigated and non-irrigated corn and soybeans and three grassland cover types were selected across the state of Nebraska. Statistical analyses revealed that the majority of the land cover pixels experienced significantly higher daytime and nighttime LSTs and lower NDVI during the drought-year growing season ( p
  • Authors:
    • Czymmek, K. J.
    • Chase, L. E.
    • Ketterings, Q. M.
    • Swink, S. N.
    • van Amburgh, M. E.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 1
  • Year: 2011
  • Summary: New York (NY) has dairy, cash grain, fruit, and vegetable industries located in close proximity to water, making it important to optimize manure and fertilizer use for both economic production of crops and protection of the environment. The gross phosphorus (P) balance for NY (manure and fertilizer P minus crop P removal) estimated for 2006 was +1.7 kg ha(-1) (+1.5 lb ac(-1)), indicating that, on a statewide basis, P is in balance. Our objectives in this study were to (1) estimate state, regional, and county-level gross nitrogen (N) balances for NY for 2007; (2) evaluate N balance trends over time (1987, 1992, 1997, 2002, and 2007); (3) estimate nonlegume cropland (net) N balances for 2007; and (4) quantify the potential impact of improved herd nutrition and manure incorporation on N balances. The 2007 NY gross N balance for nonlegume cropland was +62 kg ha(-1) (+55 lb ac(-1)). Long Island and western NY had the highest N balances (+101 and +77 kg ha(-1) [+90 and +69 lb ac(-1)], respectively) reflecting N fertilizer use for horticultural and/or cash grain crops (both regions) and presence of a concentrated dairy industry (western NY). The Chesapeake Bay watershed and Lake Champlain Basin counties had gross N balances below +28 kg ha(-1) (+25 lb ac(-1)). The statewide N balance decreased from +125 kg ha(-1) (+112 lb ac(-1)) in 1987 to +62 kg ha(-1) (+55 lb ac(-1)) in 2007, largely driven by a decline in N fertilizer use between 1987 and 1992. The statewide N balance dropped to -38 kg ha(-1) (-34 lb ac(-1)) when manure N losses in the barn and storage system and at land application were taken into account. Given a nearly zero P balance, a negative N balance indicates the need for best management practices that increase N use efficiency of manure and fertilizer and/or add N from other sources (cover crops, greater reliance on N fixation, shorter rotations). Improvement in herd nutrition through precision feeding has the potential to increase N use efficiency of surface applied manure and thus reduce N loss to the environment. However, such improvements will also reduce the total amount of N excreted and decrease the N:P ratio of the manure. Best management practices that reduce N loss in the barn and storage system, increase manure and fertilizer N uptake efficiency, and/or reduce N needs will be essential in order to balance N and P for the long-term sustainability of NY agriculture.
  • Authors:
    • Budzynski, W.
    • Szemplinski, W.
  • Source: ACTA Scientiarum Polonorum, Agricultura
  • Volume: 10
  • Issue: 2
  • Year: 2011
  • Summary: The paper comprises a review of the results of studies on cereal mixtures published in 2003-2007 in the Polish scientific literature. There are presented herein the most important issues concerning yield ability, weed, pest and diseases infestation. Cereal mixtures occupy the highest area among spring cereals in Poland and grain harvested from mixtures plays an important role in production of feedstock in the country. The highest concentration of mixtures is noted in the eastern region and the lowest in the south-western part of Poland. The higher yield ability of mixtures compared to pure cereal stands is connected with complementary utilization of environmental resources in different time, space (under- or aboveground) or form (water, light, nutrients) by mixtures' components as well as with competition, responsible for changes in proportion of components in the mixture yield. The better stability of yield is attributed to a better competition ability against weeds and lower susceptibility of mixtures to diseases compared to pure stands. Mixed stands show a better response to some agronomical factors, such as irrigation, mineral fertilization and chemical protection against pests, weeds and diseases. A higher proportion of naked forms of barley and oat in mixtures has been recommended recently. Therefore, the mixture yields are lower than those of mixtures with hulled forms but their feeding value is higher, because of a lower content of fibre and a higher content of protein and fat.
  • Authors:
    • Calin, L.
    • Taranu, I.
    • Tabuc, C.
  • Source: Archiva Zootechnica
  • Volume: 14
  • Issue: 4
  • Year: 2011
  • Summary: Fungal mycoflora and mycotoxin contamination were determined in 86 samples (21 maize, 21 wheat, 11 barley, 4 oats, 1 rye, 12 soya, 6 sunflower, 4 colza, 3 rice, 3 triticale), coming from the south-eastern part of Romania during the 2008 to 2010 period. The most frequent fungal contaminants belonged to the Aspergillus and Fusarium genera, maize was the most contaminated cereal. The main toxinogenic species identified were A. flavus, A. fumigatus, F. graminearum, F. culmorum in all cereals Aflatoxin B1 (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZEA) and fumonisins (FUMO), contents were analyzed by ELISA. More than 90% of the samples were found to be contaminated by at least one toxin. The most frequent mycotoxin was the deoxynivalenol (71.60%). Around 40% of samples were contaminated with AFB1 and FB. Ochratoxine A and zearalenone were found in 16% and 32% of samples respectively. These results demonstrated that cereals produced in Romania present a particular pattern of fungal mycoflora and mycotoxin contamination since DON, ZEA and FUMO as well as AFB1 and OTA were observed.
  • Authors:
    • LaFond, G. P.
    • May, W. E.
    • Tenuta, M.
    • Entz, M. H.
    • Turmel, M. S.
  • Source: Canadian Journal of Plant Science
  • Volume: 91
  • Issue: 6
  • Year: 2011
  • Summary: Leguminous cover crops are becoming a popular way to increase the sustainability of agricultural systems. Previously, cover crops have been found to increase colonization by arbuscular mycorrhizal fungi (AM F) and phosphorus and micronutrient uptake. Long-term field studies were conducted to test the hypothesis that self-regenerating black medic (Medicago lupulina cv. George) cover crops increase AM F colonization and early nutrient uptake in flax (Linum usitatissimum). Field experiments were established in 2000 (Manitoba) and 2002 (Saskatchewan) using a flax wheat (Triticum aestivum) oat (Avena sativa) rotation. In a second experiment, intact soil cores were harvested from the plots in spring and tested for soil disturbance and cover crop effects under controlled environment conditions (CEC). Both seedling flax crops sampled from the field in 2005 and 2006 and flax growth in CEC showed high levels of AMF root colonization, but no significant influence of the cover crop on AM F colonization by arbuscules or hyphal structures was detected. The AMF enhancing practices used in the experiments (i.e., zero-tillage and inclusion of mycorrhizal crops) may have contributed to the lack of cover crop effect on AMF colonization. The cover crop had no effect on macro- or micronutrient uptake by flax except during drought conditions (Winnipeg 2006), where flax biomass was reduced by 38% and the total uptake of N, P, Zn and Cu was decreased by 34, 30, 31 and 35%, respectively, in the medic treatment.
  • Authors:
    • Dobermann, A. R.
    • Shapiro, C. A.
    • Tarkalson, D. D.
    • Wortmann, C. S.
    • Ferguson, R. B.
    • Hergert, G. W.
    • Walters, D.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 1
  • Year: 2011
  • Summary: Nitrogen use efficiency (NUE) is of economic and environmental importance. Components of NUE were evaluated at in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska with different N rates and where the previous crop was either corn (CC), drybean ( Phaseolus vulgaris L.) (CD), or soybean [Glycine max (L.) Merr.] (CS). The mean grain yield with adequate nutrient availability was 14.7 Mg ha -1 When no N was applied, measured soil properties and irrigation water N accounted for <20% of the variation in plant nitrogen uptake (UN). Mean fertilizer N recovery in aboveground biomass was 74% at the lowest N rate compared with 40% at the highest N rate, a mean of 64% at the economically optimal nitrogen rate (EONR), and least with CD. Agronomic efficiency of fertilizer N averaged 29 kg grain kg(-1) N at EONR and was also least with CD. Partial factor productivity of N averaged 100 kg grain kg(-1) N at EONR, and was greater with CS compared with CC and CD. Aft er harvest, residual soil nitrate nitrogen (RSN) in the 0- to 1.2-m depth ranged from 21 to 121 kg ha(-1) and increased with N rate. Mean RSN was 88, 59, and 59 kg ha(-1) for CD, CC, and CS, respectively. High corn yields can be achieved with high NUE and low RSN by management to maximize profitability in consideration of yield potential, and by applying N at the right amount and time.
  • Authors:
    • Schultz, R. C.
    • Zaimes, G. N.
  • Source: Ecological Engineering
  • Volume: 37
  • Issue: 11
  • Year: 2011
  • Summary: Extensive land-use changes in Iowa have increased erosional processes and the amount of fines deposited on stream beds. Large amounts of fines cover the other bed substrate that are essential habitat for invertebrates and fish. In Iowa and other agricultural Midwestern states, riparian conservation land-uses are being established to minimize sediment inputs to streams. This study compared stream bed substrate composition in reaches adjacent to: riparian forest buffers, grass filters, row-cropped fields, pastures with cattle fenced out of the stream and continuous, rotational and intensively grazed rotational pastures, in three regions of Iowa. The objective was to examine the impacts of the adjacent riparian land-uses on stream bed substrate composition. The percentages of fines in this study ranged from: 36 to 63% in the central region; 10 to 31% in the northeast region; and 22 to 85% in the southeast region. The high percentage of fines in most stream bed reaches indicates high embeddedness. The high embeddedness resulted in the few significant differences in substrate percentages among riparian land-uses. Decades of agricultural land-uses have heavily impacted stream beds and only significant reductions in surface and bank erosion at the watershed scale can begin to reverse this trend. There were indications that riparian forest buffers and to a lesser degree, pastures with cattle fenced out of the stream, could decrease fines resulting in a more diverse substrate composition. Overall, more targeted approaches for the establishment of conservation land-uses in combination with other restoration practices (e.g. in-stream enhancements) are required to successfully decrease fines on stream beds. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Kocourkova, D.
    • Neckar, K.
    • Fuksa, P.
    • Pivec, J.
    • Brant, V.
    • Venclova, V.
  • Source: Biomass and Bioenergy
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: The biomass production dynamics of catch crops, volunteers and weeds in dependence on precipitation and air temperature, was studied in central Bohemia from 2004 to 2006. The cover of individual components of the growth was monitored during the same period. Also measured were energy and efficiency of utilization of global radiation by catch crops and volunteers. The catch crops included the following species: Brassica napus, Lolium multiforum, Lolium perenne, Phacelia tanacetifolia, Sinapis alba, Trifolium incarnatum, Raphanus sativus var. oleiformis and Trifolium subterraneum. The highest biomass production and the highest cover of catch crops were observed in treatments with S. alba (1382.0 kg ha(-1), 47.8%). The average biomass production (sum of catch crops, volunteers and weeds) was highest in treatments with S. alba, R. sativus, and P. tanacetifolia and lowest in treatments with B. napus, L. multiflorum and L. perenne. It was demonstrated that an increase in the percentage share of volunteers caused a decrease in the biomass production of catch crops. The average energy production ranged from 0.31 to 2.37 MJ m(-2) in treatments with catch crops, and from 0.25 to 0.89 MJ m(-2) in treatments with cereal volunteers. The highest effectivity of global radiation utilization, was determined in treatments with S. alba (0.11-0.47%). Based on regression analysis the closest dependence between biomass production from all treatments on the experimental site and precipitation was observed from 1st May till the time of sowing and the average air temperatures from the sowing period till the time of the last biomass production assessment. (C) 2010 Elsevier Ltd. All rights reserved.