• Authors:
    • Lal, R.
    • Blanco-Canqui, H.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Franzluebbers (2009) is right about the need for a more intensive soil sampling, "repeated sampling with time,"and "stratified sampling" as well as for the use of multiple fields and collection of larger number of pseudoreplicates to overcome the high field variability in soil organic carbon (SOC) pools within each Major Land Resource Area (MLRA). The selected fields were representative of each MLRA in terms of soil type, slope, and management, but it is correct that a single soil would not capture all the variability in soil and management for the whole MLRA. This study was not intended to relate the data from the single soil to the whole MLRA but rather to emphasize the differences in SOC sequestration rates among the three management systems within each soil.
  • Authors:
    • Sousa, P.
    • Hansen, M. N.
    • Blanes-Vidal, V.
  • Source: Journal of Environmental Quality
  • Volume: 38
  • Issue: 4
  • Year: 2009
  • Summary: Swine (Sus scrofa) slurry stored in open storages is a source of airborne contaminants. A customary practice for ammonia and odor control consists of covering the surface of the slurry with floating materials, such as straw. Although straw covers have been proven to generally reduce gaseous emissions, more knowledge is needed regarding how age, moisture content, and microbiological development of the straw cover affect the emissions of odor and odorants to develop recommendations for the practical use of straw covers. This study compiles data on odor concentration and odorants above swine slurry covered by straw of different ages and moisture contents, during a 9 wk laboratory scale study. The results showed that aged straw covers significantly reduced emissions of ammonia (by 99%), dimethyl sulfide (by 81%), phenol (82%), p-cresol (by 95%), skatole (by 98%), and benzylalcohol (by 97%), while no significant differences were found between uncovered and covered slurry for emission of odor, hydrogen sulfide, volatile fatty acids, dimethyl disulfide, and indole. The moisture content of the straw cover neither affected emissions of odor nor odorants. This study suggests that the main mechanism for odor and odorants emission reduction from straw covered slurry is as a physical barrier and not as a biofilter. However, the reduction in emissions of specific gases (such as ammonia, dimethyl sulfide, p-cresol, and benzyl alcohol) appears to be also caused by the straw cover acting as a biofilter.
  • Authors:
    • Pepo, P.
  • Source: Cereal Research Communications
  • Volume: 37
  • Issue: Suppl. 1
  • Year: 2009
  • Summary: The effects of different water supply cropyears (2007 year=dry, with water stress; 2008 year=optimum water supply) on the yields and agronomic traits of wheat in different crop models (crop rotation, fertilization, irrigation) were studied. In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha -1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. In water-deficit stress cropyear (2007 year) the yield-surpluses of wheat were 2245 kg ha -1 (biculture) and 1213 kg ha -1 (triculture), respectively. The nutrient utilization of wheat was modified by abiotic (water) and biotic (leaf- and stem-diseases) stress. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N 150-200+PK in biculture and N 50-150+PK in triculture depending on cropyear and irrigation. The abiotic stress (water deficit) influenced the agronomic traits (diseases, lodging) of winter wheat. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively.
  • Authors:
    • Pepo, P.
  • Source: Analele Universităţii din Oradea, Fascicula: Protecţia Mediului
  • Volume: 14
  • Year: 2009
  • Summary: In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha -1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N 150-200+PK in biculture and N 50-150+PK in triculture depending on cropyear and irrigation. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively. Our scientific results proved that in water stress cropyear (2007) the maximum yields of maize were 4316 kg ha -1 (monoculture), 7706 kg ha -1 (biculture), 7998 kg ha -1 (triculture) in non irrigated circumstances and 8586 kg ha -1, 10 970 kg ha -1, 10 679 kg ha -1 in irrigated treatment, respectively. In dry cropyear (2007) the yield-surpluses of irrigation were 4270 kg ha -1 (mono), 3264 kg ha -1 (bi), 2681 kg ha -1 (tri), respectively. In optimum water supply cropyear (2008) the maximum yields of maize were 13 729-13 787 (mono), 14 137-14 152 kg ha -1 (bi), 13 987-14 180 kg ha -1 (tri) so there was no crop-rotation effect. We obtained 8,6-11,0 t ha -1 maximum yields of maize in water stress cropyear and 13,7-14,2 t ha -1 in optimum cropyear on chernozem soil with using appropriate agrotechnical elements.
  • Authors:
    • Vyn, T.
    • McIntyre, L.
    • Brewer, J.
    • West, T.
    • Santini, J.
    • Boomsma, C.
  • Source: Soil & Tillage Research
  • Volume: 106
  • Issue: 2
  • Year: 2009
  • Summary: Research emphasizing slower plant growth and delayed maturity in continuous maize ( Zea mays L.), no-till (MM-NT) systems has often led to the conclusion that lower grain yields in this environment are associated with reduced plant heights. Yet prior research has shown that early-season and mature plants are not always shorter in MM-NT systems, suggesting that overall plant height may not be an accurate morphometric indicator of decreased yield in MM-NT environments. Given that plant-to-plant morpho-physiological uniformity is strongly associated with higher yield in maize, we hypothesized that greater plant height variability would provide a better agronomic explanation for yield loss in MM-NT environments than overall plant height reductions. This 14-year study primarily examined the effects of crop rotation {maize-soybean [ Glycine max (L.) Merr.] and continuous maize} and tillage system (no-till and moldboard plow) on the yield, 4-week plant population, and 4- and 8-week plant height and plant height variability of a single maize cultivar. Due to sizeable year-to-year variation, actual crop response means for the MM-NT; maize-soybean, no-till (MB-NT); and continuous maize, moldboard plow (MM-PL) treatment combinations were expressed relative to the accompanying means for the maize-soybean, moldboard plow (MB-PL) treatment. In numerous years, the MM-NT system exhibited reduced actual and relative yields and lower 4- and 8-week plant heights compared to the other treatment combinations. Both actual and relative 4- and 8-week plant height variability were rarely greatest for the MM-NT treatment, and in only a few years were actual and/or relative plant density lowest for this system. However, single-factor regression analyses between relative yield and the aforementioned relative agronomic measures revealed that a decline in relative MM-NT yield was most strongly associated with an increase in relative 4-week plant height variability. Multi-factor regression analyses between relative yield, relative 4-week plant height variability, and various weather parameters suggested that this strong inverse relationship was potentially a manifestation of (i) non-uniform germination, emergence, and early seedling growth and (ii) later-season intra-specific competition. Regression analyses between relative 4-week plant height variability and various weather parameters suggested that phenomenon (i) was potentially promoted by cool and moist or warm and dry pre-plant weather conditions while phenomenon (ii) was possibly encouraged by low precipitation and/or high temperatures during rapid stem elongation. While MM-NT systems should be managed to limit plant density reductions and minimize growth and developmental delays, increased focus should be placed on minimizing the occurrence of plant-to-plant variability in these environments.
  • Authors:
    • Mozny, M.
    • Zalud, Z.
    • Dubrovsky, M.
    • Semeradova, D.
    • Trnka, M.
    • Hlavinka, P.
  • Source: Agricultural and Forest Meteorology
  • Volume: 149
  • Issue: 3-4
  • Year: 2009
  • Summary: The relationship between seasonal agricultural drought and detrended yields (within a period from 1961 to 2000) of selected crops was assessed in the conditions of the Czech Republic, which are to some extent representative of a wider area of Central Europe. Impact of water stress was analyzed using time series of yields for 8 crops (spring barley, winter wheat, grain maize, potato, winter rape, oats, winter rye and hay from permanent meadows) for 77 districts in the Czech Republic (average district area is 1025 km(2)). Relative version of Palmer's Z-index (rZ-index or rZ-i) was used as a tool for quantification of agricultural drought. The monthly values of the rZ-index for each individual district were calculated as the spatial average (only for the grids of arable land). The study showed that severe droughts (e.g., in 1981 and 2000) are linked with significant reduction in yields of the main cereals and majority of other crops through the most drought prone regions. We found a statistically significant correlation (p
  • Authors:
    • Barbercheck, M. E.
    • Jabbour, R.
  • Source: Biological Control
  • Volume: 51
  • Issue: 3
  • Year: 2009
  • Summary: The growing demand for organic products creates opportunities for farmers. Information on the consequences of management practices can help farmers transition to organic and take advantage of these prospects. We examined the interaction between soil disturbance and initial cover crop on naturally occurring entomopathogenic fungi (EPF) during the 3-year transition to organic production in a feed grain rotation in central Pennsylvania. Our experiment included four systems comprised of a factorial combination of two levels of primary tillage (full vs. reduced) and two types of initial cover crop (timothy/clover vs. rye/vetch). The cropping sequence consisted of an initial cover crop, followed by soybean, and finally, maize. The entire experiment was replicated in time, with the initiation lagged by 1 year. We detected four species of EPF (Metarhizium anisopliae, Beauveria bassiana, Isaria fumosorosea, and Isaria farinosa) by bioassay of soil samples collected four times during each field season. The latter three species were detected infrequently; therefore, we focused statistical analysis on M. anisopliae. Detection of M. anisopliae varied across sampling date, year in crop sequence, and experimental start, with no consistent trend across the 3-year transition period. M. anisopliae was isolated more frequently in the systems initiated with timothy/clover cover crops and utilizing full tillage; however, we only observed a tillage effect in one temporal replicate. M. anisopliae detection was negatively associated with soil moisture, organic matter, and zinc, sulfur, and copper concentrations in the soil. This study helps to inform farmers about management effects on soil function, specifically conservation biological control. (C) 2009 Elsevier Inc. All rights reserved.
  • Authors:
    • Thelen, D.
    • Kravchenko, A.
  • Source: Journal of Sustainable Agriculture
  • Volume: 33
  • Issue: 5
  • Year: 2009
  • Summary: Wheat ( Triticum aestivum L.) crop residue can negatively affect the growth and development of no-till corn ( Zea mays L.). The objective of this study was to determine whether nitrogen management practices including legume cover crops and manure applications used in conjunction with a pre-sidedress soil nitrate test (PSNT) could be used to overcome the observed wheat residue antagonism of no-till corn growth and development. A PSNT nitrogen strategy was effective in maintaining no-till corn grain yield in wheat residue systems equivalent to no-till corn grain yield in no-wheat residue systems in 4 of 6 site years. Similar results were obtained for PSNT plus clover cover crop and PSNT plus manure plus clover cover crop nitrogen management systems. Utilization of a PSNT with manure application equalized no-till corn grain yield in high wheat residue treatments with no-till corn grain yield in treatments without wheat residue in all site years. This can be a recommended practice in the Michigan eco-region.
  • Authors:
    • Kremer, R. J.
    • Kussman, R.
  • Source: Agroforestry comes of age: putting science into practice. Proceedings of the 11th North American Agroforestry Conference, Columbia, Missouri, USA, 31 May - 3 June, 2009
  • Year: 2009
  • Summary: Intercropping alleys of agroforestry systems provides an income source until the tree crop produces harvestable yields. However, cultivation of annual crops soil organic matter and increases soil erosion, especially on sloping landscapes. Perennial crops maintain a continuous soil cover, maximize water infiltration, minimize soil erosion, and improve overall soil quality. The objective of this on-farm study was to assess the effects of a perennial legume, kura clover ( Trifolium ambiguum), on various soil quality parameters in a recently established pecan ( Carya illinoinensis) orchard. The pecan-kura clover agroforestry system was established on deep loess soils of the Missouri River hills. These silt loams are on 3 to 10% slopes and can be highly erosive. Kura clover, intercropped eight years after pecan planting, was selected based on its perennial growth habit, nitrogen-fixing ability, winter hardiness, high forage quality, and soil conservation properties. Kura clover was seeded in 2002 and harvested for hay annually beginning 2003. During this period soil organic matter and activities of selected soil enzymes have steadily increased compared with cultivated and grass pasture control soils. Water-stable aggregation improved by 50%. Results illustrate that kura clover as the interplanted component improved soil fertility and biological activity through increased organic matter and improved soil structure, and yielded high quality forage valuable for the cattle-feeding operation. Pecan trees thrive in this system partly because soil quality is maintained or improved and, unlike other "living mulch" systems in which cover crops may suppress the main crop, kura clover does not compete with tree growth.
  • Authors:
    • Bernards, M. L.
    • Wilson, R. G.
    • Jordan, D. L.
    • Wilcut, J. W.
    • Shaw, D. R.
    • Owen, M. D. K.
    • Weller, S. C.
    • Johnson, W. G.
    • Kruger, G. R.
    • Young, B. G.
  • Source: Weed Technology
  • Volume: 23
  • Issue: 1
  • Year: 2009
  • Summary: Corn and soybean growers in Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina, as well as cotton growers in Mississippi and North Carolina, were surveyed about their views on changes in problematic weeds and weed pressure in cropping systems based on a glyphosate-resistant (GR) crop. No growers using a GR cropping system for more than 5 yr reported heavy weed pressure. Over all cropping systems investigated (continuous GR soybean, continuous GR cotton, GR corn/GR soybean, GR soybean/non-GR crop, and GR corn/non-GR crop), 0 to 7% of survey respondents reported greater weed pressure after implementing rotations using GR crops, whereas 31 to 57% felt weed pressure was similar and 36 to 70% indicated that weed pressure was less. Pigweed, morningglory, johnsongrass, ragweed, foxtail, and velvetleaf were mentioned as their most problematic weeds, depending on the state and cropping system. Systems using GR crops improved weed management compared with the technologies used before the adoption of GR crops. However, the long-term success of managing problematic weeds in GR cropping systems will require the development of multifaceted integrated weed management programs that include glyphosate as well as other weed management tactics.