• Authors:
    • Ferguson, R.
    • Boquet, D.
    • Paxton, K.
  • Source: Louisiana Agriculture
  • Volume: 54
  • Issue: 2
  • Year: 2011
  • Summary: An experiment was conducted from 2001 to 2009 in Louisiana to analyze the profit potential of a soyabean/wheat double-crop was compared to a monocrop system. Wheat was planted in early to mid-November each year, and soybeans were planted immediately following wheat harvest, generally in mid-May. Monocrop soybeans were generally planted in late April or early May. The difference in yield for the duration of the experiment averaged about 3.6 bushels per acre. Although the double-crop soyabeans had lower average yields, this system also had additional income from the wheat crop. Wheat yields ranged from about 40 to almost 80 bushels per acre and averaged 58 bushels per acre from 2002 through 2009. For most of the years, the double-crop system produced higher net returns than soyabeans alone. During the experiment, the double-crop system net returns were 58.89 dollars per acre higher than the monocrop soybeans. Based on this analysis, double cropping soybeans and wheat could add significantly to a producer's net income.
  • Authors:
    • Dias, T.
    • Correa, M.
    • Alves, P.
    • Pereira, R.
  • Source: Revista Brasileira de Ciências Agrárias
  • Volume: 6
  • Issue: 1
  • Year: 2011
  • Summary: The success in weed control by using straw depends on the management time, straw quality and quantity. The objective of this research was to evaluate the suppressor effect of black-oats and millet straw cover on the incidence of weeds and on the productivity of the soybean crop. The experiment was carried out during the years 2006 and 2007, in an area from the Farm of Education, Research and Produtcion of FCAV-UNESP, Jaboticabal Campus, in a completely randomized block design, with four replications. Treatments consisted of different types of black oats and pearl millet straw management before soybean seeding (without management, obtained by machine cut, desiccated using glyphosate desiccation and with paraquat) and different periods of straw deposition (0, 15, 30 e 60 days before soybean seeding). The weed population and the characteristics of soybean growth and production were evaluated. The deposition of black oats and pearl millet straw provided reductions in weed density and dry mass, and this effect was more effective when the deposition occurred until 15 days prior to soybean seeding. The suppressor effect of black oats straw was more pronounced than that of pearl millet straw, regardless of the drying method, although the millet had a greater dry matter production. No significant differences were found between the drying methods and the straw effectiveness.
  • Authors:
    • Spera, S.
    • Fontaneli, R.
    • Santos, H.
    • Maldaner, G.
  • Source: PESQUISA AGROPECUARIA BRASILEIRA
  • Volume: 46
  • Issue: 10
  • Year: 2011
  • Summary: The objective of this work was to assess energy conversion and balance of integrated crop-livestock production systems, under no-tillage. The experiment was carried out from 2001 to 2008. From 2001 to 2002, the following systems were evaluated: 1, wheat/soybean, and black oat pasture+common vetch/corn; 2, wheat/soybean, and black oat pasture+common vetch+ryegrass/corn; 3, wheat/soybean and black oat pasture+common vetch/millet pasture; 4, wheat/soybean and black oat pasture+common vetch+rygrass/millet pasture; 5, wheat/soybean, white oat/soybean, and black oat pasture+common vetch/millet pasture; 6, wheat/soybean, white oat/soybean, and black oat pasture+common vetch+rygrass/millet pasture. From 2003 to 2008, the following systems were evaluated: 1, wheat/soybean, and common vetch/corn; 2, wheat/soybean, and black oat pasture/corn; 3, wheat/soybean, and black oat pasture/soybean; 4, wheat/soybean, and field pea/corn; 5, wheat/soybean, common vetch/soybean, and double purpose triticale/soybean; and 6, wheat/soybean, double purpose white oat/soybean, and double purpose wheat/soybean. Corn showed highest returned energy in comparison to the other grain crops, and to winter and summer annual pastures. Of the winter cover crops and green manure species evaluated, field pea was the most efficient in energy conversion. Systems 1, 2, and 4, from 2003 to 2008, had the most efficient energy balance.
  • Authors:
    • Yang, W.
    • Liu, W.
    • Wan, Y.
    • Zhang, J.
    • Xiang, D.
    • Yong, T.
  • Source: Acta Prataculturae Sinica
  • Volume: 20
  • Issue: 6
  • Year: 2011
  • Summary: The aim of this paper was to study the mechanisms of interspecific nitrogen facilitation and transfer in the relay strip intercropping systems of "wheat/maize/soybean" and "wheat/maize/sweet potato". The methods of root barrier and 15N-isotope dilution were used to investigate the nitrogen transfer, nitrogen uptake and residual effect in the two relay strip intercropping systems. Comparing the no barrier with solid barrier, the results showed that in-season 15N uptake and 15N recovery efficiency of wheat increased remarkably, and 15N% abundance left in soil and total N content reduced obviously. In the "wheat/maize/soybean" system, the in-season 15N uptake and 15N recovery efficiency, 15N% abundance left in soil and total N content of maize with no barrier increased by 25.16%, 25.16%, 13.89% and 10.15%. But in the "wheat/maize/sweet potato" system, the value of above indices reduced by 15.98%, 15.99%, 17.37% and 5.19%. For soybean, the in-season 15N uptake and 15N recovery efficiency, 15N% abundance left in soil reduced, the soil total N content increased by 3.03%. For sweet potato, the in-season 15N uptake and 15N recovery efficiency increased, 15N% abundance left in soil and total N content reduced by 0.91% and 4.95%. In the "wheat/maize/soybean" system, the 15N uptake and 15N recovery efficiency of wheat and maize obtained from previous wheat, maize and soybean were higher than that of the "wheat/maize/sweet potato" system. The 15N uptake and 15N recovery efficiency of soybean obtained from previous wheat or maize were lower than that of sweet potato, but that from previous soybean was higher than that from previous sweet potato. The "wheat/maize/soybean" system was more beneficial to increase annual nitrogen uptake, nitrogen residual effect and maintaining soil fertility.
  • Authors:
    • Dalgliesh, N. P.
    • Nelson, R.
    • Khan,I. A.
    • Carberry, P. S.
    • Kabir, M. J.
    • Poulton, P. L.
  • Source: ACIAR Technical Reporst No.78, Australian Centre for International Agricultural Research, Canberra, H. Rawson (ed), Canberra, ACT[Research Book Chapter]
  • Issue: 78
  • Year: 2011
  • Summary: Increased Rabi-season crop production in southern Bangladesh could help meet the country's growing food demand. This paper reports on an assessment of the economic viability of wheat and other Rabi-season crops based on farmer surveys of crop yields and economic performance. In addition, it considers the agroeconomic and socioeconomic factors that influence farmers' choice of Rabi-season crops. Current Rabi-season crops in southern Bangladesh include boro rice and vegetable production on lands with irrigation facilities. A range of other crops are grown, with and without irrigation, including chilli, potato, grasspea, chickpea, mungbean and soybean. Although farmers in some southern regions had grown wheat in the past, wheat is not a significant crop across the region. The recent increased interest in wheat in some villages corresponded to project activities of a development project, funded by the Australian Centre for International Agricultural Research (ACIAR) and specifically to the availability of newly released varieties with higher yield potential and disease resistance. In those villages where project trials were conducted, irrespective of seasonal conditions, wheat-based rotations provided higher gross margins than the alternative crops of chilli and cowpea. Even in a relatively poor season, wheat offered a significantly higher gross margin and thus lower risk than the other crops. However, the crop establishment costs of wheat are high and wheat requires at least one irrigation when many farmers lack any irrigation facilities. Formal education, off-farm income and farming experience are the socioeconomic factors that displayed significant positive correlation to the surveyed farmers' decision to adopt wheat production. This study confirmed the economic viability of Rabi cropping in southern Bangladesh. While the crops currently grown in the Rabi season are profitable under most seasonal conditions, this study confirmed that wheat offers farmers a profitable and low-risk option.
  • Authors:
    • Stevenson, F. C.
    • Legere, A.
    • Benoit, D. L.
  • Source: Weed Science
  • Volume: 59
  • Issue: 1
  • Year: 2011
  • Summary: A conservation tillage study provided the opportunity to test whether tillage effects on the germinable weed seedbank would be consistent across different crop rotations and to investigate the potential residual effects of herbicide treatments terminated 12 yr earlier. Our objective was to measure the effects of tillage (moldboard plow [MP] vs. chisel plow [CP] vs. no-till [NT]), crop rotation (2-yr barley-red clover followed by 4-yr barley-canola-wheat-soybean rotation, compared to a cereal monoculture), and of a prior weed management factor (three intensity levels of herbicide use) on the density, diversity, and community structure of weed seedbanks. Species richness, evenness (Shannon's E), and diversity (Shannon's H′) of spring seedbanks varied little across treatments and over time. Total seedbank density generally increased as tillage was reduced, with some variations due to weed management in 1993 and crop rotation in 2006. Crop rotations generally had smaller seedbanks with fewer species than the monoculture. In 1993, seedbanks with minimum weed management were twice as dense as those with intensive or moderate weed management (approximately 6,000 vs. 3,000 seed m -2). By 2006, seed density averaged 6,838 seed m -2 across intensive and moderate weed management regardless of tillage, but was nearly twice as large in NT (12,188 seed m -2) compared to MP (4,770 seed m -2) and CP (7,117 seed m -2) with minimum weed management (LSD 0.005=4488). Species with abundant seedbanks responded differently to treatments. Barnyardgrass and green foxtail had larger seedbanks in the monoculture than in the rotation. Common lambsquarters and pigweed species had large seedbanks in tilled treatments in the rotation, whereas yellow foxtail and field pennycress contributed to the large seedbanks observed in NT treatments. The latter two species were also associated with residual effects of weed management treatments (terminated 12 yr earlier) in NT. The differential seedbank response of weed species, attributed in part to contrasting weed emergence patterns and agronomic practice effects on seed rain, explained some of the weak treatment effects observed for total seedbank density and diversity. The large weed seedbanks observed in NT plots after 18 yr confirms the importance of seed rain and seedbank management for the sustainability of NT systems.
  • Authors:
    • Byrant, G.
    • White, I.
    • Denmead, O. T.
    • Macdonald, B. C. T.
  • Source: Pedosphere
  • Volume: 21
  • Issue: 2
  • Year: 2011
  • Authors:
    • Blanco-Canqui, H.
    • Mikha, M. M.
    • Presley, D. R.
    • Claassen, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Inclusion of cover crops (CCs) may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a winter wheat ( Triticum aestivum L.)-grain sorghum [ Sorghum bicolor (L.) Moench] rotation, four N rates, and a hairy vetch (HV; Vicia villosa Roth) CC after wheat during the first rotation cycles, which was replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean [LMS; Glycine max (L.) Merr.] CCs in no-till on a silt loam. At the end of 15 yr, we studied the cumulative impacts of CCs on soil physical properties and assessed relationships between soil properties and soil organic C (SOC) concentration. Across N rates, SH reduced near-surface bulk density (rho b) by 4% and increased cumulative infiltration by three times relative to no-CC plots. Without N application, SH and LMS reduced Proctor maximum rho b, a parameter of soil compactibility, by 5%, indicating that soils under CCs may be less susceptible to compaction. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0- to 7.5-cm depth. The SOC concentration was 30% greater for SH and 20% greater for LMS than for no-CC plots in the 0- to 7.5-cm depth. The CC-induced increase in SOC concentration was negatively correlated with Proctor maximum rho b and positively with MWDA and cumulative infiltration. Overall, addition of CCs to no-till systems improved soil physical properties, and the CC-induced change in SOC concentration was correlated with soil physical properties.
  • Authors:
    • Calonego, J. C.
    • Rosolem, C. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Soil water availability to plants is affected by soil compaction and other variables. The Least Limiting Water Range (LLWR) comprises soil physical variables affecting root growth and soil water availability, and can be managed by either mechanical or biological methods. There is evidence that effects of crop rotations could last longer than chiseling, so the objective of this study was to assess the effect of soil chiseling or growing cover crops under no-till (NT) on the LLWR. Crop rotations involving triticale (X Triticosecale) and sunflower (Helianthus annuus) in the fall-winter associated with millet (Pennisetum glaucum), sorghum (Sorghum bicolor) and sunn hemp (Crotalariajuncea) as cover crops preceding soybean (Glycine max) were repeated for three consecutive years. In the treatment with chiseling (performed. only in the first year), the area was left fallow between the fall-winter and summer crops. The experiment was carried out in Botucatu, Sao Paulo State, Brazil, from 2003 to 2006 on a Typic Rhodudalf. The LLWR was determined in soil samples taken from the layers 0-20 cm and 20-40 cm, after chemical desiccation of the cover crops in December of the first and third year of the experiment. Chiseling decreases soil bulk density in the 0-20 cm soil layer, increasing the LLWR magnitude by lowering the soil water content at which penetration resistance reaches 2.0 MPa; this effect is present up to the third year after chiseling and can reach to a depth of 0.40 in. Crop rotations involving sunflower + sunn hemp, triticale + millet and triticale + sunn hemp for three years prevented soil bulk density from exceeding the critical soil bulk density in the 0-0.20 in layer. This effect was observed to a depth of 0.40 m after three years of chiseling under crop rotations involving forage sorghum. Hence, chiseling and some crop rotations under no tillage are effective in increasing soil quality assessed by the LLWR.
  • Authors:
    • Cheng, L.
    • Booker, F. L.
    • Burkey, K. O.
    • Tu, C.
    • Shew, H. D.
    • Rufty, T. W.
    • Fiscus, E. L.
    • Deforest, J. L.
    • Hu, S. J.
  • Source: PLOS ONE
  • Volume: 6
  • Issue: 6
  • Year: 2011
  • Summary: Climate change factors such as elevated atmospheric carbon dioxide (CO 2) and ozone (O 3) can exert significant impacts on soil microbes and the ecosystem level processes they mediate. However, the underlying mechanisms by which soil microbes respond to these environmental changes remain poorly understood. The prevailing hypothesis, which states that CO 2- or O 3-induced changes in carbon (C) availability dominate microbial responses, is primarily based on results from nitrogen (N)-limiting forests and grasslands. It remains largely unexplored how soil microbes respond to elevated CO 2 and O 3 in N-rich or N-aggrading systems, which severely hinders our ability to predict the long-term soil C dynamics in agroecosystems. Using a long-term field study conducted in a no-till wheat-soybean rotation system with open-top chambers, we showed that elevated CO 2 but not O 3 had a potent influence on soil microbes. Elevated CO 2 (1.5 * ambient) significantly increased, while O 3 (1.4 * ambient) reduced, aboveground (and presumably belowground) plant residue C and N inputs to soil. However, only elevated CO 2 significantly affected soil microbial biomass, activities (namely heterotrophic respiration) and community composition. The enhancement of microbial biomass and activities by elevated CO 2 largely occurred in the third and fourth years of the experiment and coincided with increased soil N availability, likely due to CO 2-stimulation of symbiotic N 2 fixation in soybean. Fungal biomass and the fungi:bacteria ratio decreased under both ambient and elevated CO 2 by the third year and also coincided with increased soil N availability; but they were significantly higher under elevated than ambient CO 2. These results suggest that more attention should be directed towards assessing the impact of N availability on microbial activities and decomposition in projections of soil organic C balance in N-rich systems under future CO 2 scenarios.