• Authors:
    • Belle, R. A.
    • Dutra, L. M. C.
    • Konig, O.
    • Kuss, R. C. R.
    • Roggia, S.
    • Sturmer, G. R.
  • Source: Ciência Rural
  • Volume: 38
  • Issue: 4
  • Year: 2008
  • Summary: The effects of irrigation (supplied throughout the crop growth period or during critical periods only) and plant density (250 000 or 400 000 plants/ha) on the grain yield of soyabean were studied from January to May 2005 in Santa Maria, Rio Grande do Sul, Brazil. The grain yield did not significantly vary between the plants irrigated throughout the growth period and plants irrigated during critical periods only. The grain yield of non-irrigated plants increased by 21% when the population was increased to 400 000 plants/ha.
  • Authors:
    • Chikte, P.
    • Bhalkare, S. K.
    • Thakare, S. M.
    • Lande, G. K.
  • Source: Journal Of Cotton Research And Development
  • Volume: 22
  • Issue: 2
  • Year: 2008
  • Summary: The experiment was conducted during the kharif season of 2004-05 at Dr. PDKV, Akola to evaluate the effect of different possible intercrops on bollworm complex on cotton crop. The intercrops viz., cotton+greengram, cotton+blackgram, cotton+cowpea, cotton+sorghum, cotton+maize, cotton+marigold, cotton+soybean in 1:1 ratio alongwith a treatment of sole cotton crop were sown. The intercrop cotton+cowpea proved to be the best recording least population of spotted bollworm, American bollworm and pink bollworm as against the treatment of sole cotton crop. The highest seed cotton yield of 251 kg/ha was recorded in cotton+cowpea-intercropping system as against 160 kg/ha recorded in the sole cotton crop.
  • Authors:
    • Schlindwein, J. A.
    • Gianello, C.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 32
  • Issue: 5
  • Year: 2008
  • Summary: The change of cultivation systems from conventional to no-tillage, the change in soil sampling depth and the higher crop yields over time can influence the critical P content, fertility ranges and fertilizer doses recommended for crops. This study calibrated the soil P tests, Mehlich-1, Mehlich-3 and anion-exchange (AER) resin for soyabean, wheat and maize plants cultivated under no-tillage system, and to estimate the P fertilizer amounts for a maximum economic yield. Soil samples and yield results from several experiments under no-till and different P doses, conducted by institutions of education, research and extension of the state of Rio Grande do Sul, Brazil, were used. The calibration curves were fitted using non-linear model functions, and the levels of soil fertility and fertilizer doses for a maximum economic yield were inferred. Results indicated that the average increases in maize, wheat and soyabean yields were 47.1, 12.4 and 7.2 kg/ha per kg of P 2O 5, respectively; the determination coefficients between the relative yield and soil P concentrations were higher when the soils were separated by texture classes and were highest in the 0-10 cm than the 0-20 cm layer; the critical values of P, based on Mehlich-1 were 7.5, 15.0 and 21.0 mg/kg in the 0-20 cm layer, and of 16.0, 28.0 and 40.0 mg/kg in the 0-10 cm layer in the clay classes 1, 2 and 3, respectively. Phosphorus fertility ranges were wider by Mehlich-3 and AER as compared to Mehlich-1. The quantities of P fertilizer were higher for soyabean and maize when compared to the currently recommended quantities. The critical P concentrations are higher in soils under no-tillage with soyabean, wheat and maize in the 0-20 as well as the 0-10 cm layer. The fertility ranges by resin and Mehlich-3 were wider than by Mehlich-1. The fertilizer P quantities are higher for soyabean and maize grown under no-tillage.
  • Authors:
    • Cassman, K. G.
    • Specht, J. E.
    • Weiss, A.
    • Setiyono, T. D.
    • Dobermann, A.
  • Source: Field Crops Research
  • Volume: 108
  • Issue: 1
  • Year: 2008
  • Summary: Different approaches have been used to simulate leaf area index (LAI) in soybean ( Glycine max L. Merr). Many of these approaches require genotype-specific calibration procedures. Studies modeling LAI dynamics under optimal growth conditions with yields close to the yield potential of soybean have remained scarce. A sink-driven approach was developed and evaluated for LAI simulation in soybean under near-optimal environments. The rate of change in expanding leaf area was simulated using the first derivative of a logistic function accounting for plant population density, air temperature, and water deficit. The rate of change in senescing leaf area was also simulated using the first derivative of a logistic function, assuming monocarpic senescence that began at the flowering stage (R1). Phenology was simulated as a function of temperature and photoperiod. Data for model development and evaluation were obtained from irrigated field experiments conducted at two locations in Nebraska, where agronomic management was optimized to achieve growth at a near yield potential level. LAI simulation with the proposed model had average RMSE of 0.52 m 2 m -2 for independent data at the two locations. The proposed model has minimum input requirements. Interactions between leaf growth and source-driven processes can be incorporated in the future, while maintaining the basic physiological assumptions underlining leaf expansion and senescence.
  • Authors:
    • Follett, R. F.
    • Alley, M. M.
    • Spargo, J. T.
    • Wallace, J. V.
  • Source: Soil & Tillage Research
  • Volume: 100
  • Issue: 1/2
  • Year: 2008
  • Summary: Carbon sequestration in agroecosystems represents a significant opportunity to offset a portion of anthropogenic CO 2 emissions. Climatic conditions in the Virginia coastal plain and modern production practices make it possible for high annual photosynthetic CO 2 fixation. There is potential to sequester a substantial amount of C, and concomitantly improve soil quality, with the elimination of tillage for crop production in this region. The objectives of our research were to: (1) measure C sequestration rate with continuous no-till management of grain cropping systems of the Virginia middle coastal plain; (2) determine the influence of biosolids application history on C content and its interaction with tillage management; and (3) evaluate the impact of continuous no-till C stratification as an indicator of soil quality. Samples were collected from 63 sites in production fields using a rotation of corn ( Zea mays L.)-wheat ( Triticum aestivum L.) or barley ( Hordeum vulgare L.)/soybean double-crop ( Glysine max L.) across three soil series [Bojac (coarse-loamy, mixed, semiactive, thermic Typic Hapludults), Altavista (fine-loamy, mixed semiactive, thermic Aquic Hapludults), and Kempsville (fine-loamy, siliceous, subactive, thermic Typic Hapludults)] with a history of continuous no-till management ranging from 0 to 14 years. Thirty-two of the sites had a history of biosolids application. Five soil cores were collected at each site from 0-2.5, 2.5-7.5 and 7.5-15 cm and analyzed for bulk density and soil C. Bulk density in the 0-2.5 cm layer decreased and C stratification ratio (0-2.5 cm:7.5-15 cm) increased with increasing duration of continuous no-till due to the accumulation of organic matter at the soil surface. A history of biosolids application resulted in an increase of 4.191.93 Mg C ha -1 (0-15 cm). Continuous no-till resulted in the sequestration of 0.3080.280 Mg C ha -1 yr -1 (0-15 cm). Our results provide quantitative validation of the C sequestration rate and improved soil quality with continuous no-till management in the region using on-farm observations.
  • Authors:
    • Suzuki, L. G. A. S.
    • Alves, M. C.
    • Suzuki, L. E. A. S.
    • Rodrigues, R. A. F.
  • Source: Científica, Jaboticabal
  • Volume: 36
  • Issue: 2
  • Year: 2008
  • Summary: The objective of this study was to verify the biomass yield potential of different cover crops in a Cerrado region, in Selviria, Mato Grosso do Sul, Brazil. The work was conducted in the Experimental University Farm of the Paulista State University (UNESP). The experimental design was the randomized complete blocks in strips with splitsplit plot: the plots were the cover crops Mucuna aterrima, Pennisetum americanum, Crotalaria juncea, Cajanus cajan and a fallow area; the split plots were the no-tillage and the conventional tillage, and the splitsplit plots were corn ( Zea mays L.), soybean ( Glycine max (L.) Merrill), and cotton ( Gossypium hirsutum L.) crops. In the winter irrigated Phaseolus vulgaris L. was the crop. In the spring/summer season the cover crop with the greatest biomass yield was Pennisetum americanum. Crotalaria juncea and the fallow area showed medium results while Mucuna aterrima and Cajanus cajan were those with the least yields. Pennisetum americanum was the crop cover with the biggest production potential of dry biomass. The cultivation systems did not influence the dry biomass of the cover crops. Only Pennisetum americanum production was influenced by crop sequence.
  • Authors:
    • El-Mergawi, R.
    • Taie, H. A. A.
    • Radwan, S.
  • Source: American-Eurasian Journal of Agricultural & Environmental Science
  • Volume: 4
  • Issue: 2
  • Year: 2008
  • Summary: Soyabean intake is inversely correlated with risks of several chronic diseases in human. Phytochemicals and in particular phenolic acids, flavonoids and isoflavonoids compounds present in soyabean seeds may be partially responsible for these health benefits through their antioxidants activity. In a pot experiment, soyabean plants were grown on sandy media and irrigated with Hoagland solution as inorganic treatment or grown under one of the three levels of compost, i.e. 25, 50 and 75%, alone or in a mixture with multibioorganic. Individual phenolic acids, quercetin, genistein and daidzein in seeds were quantified by HPLC. Changes in the levels of individual phenolics and less value of quercetin under various compost levels resulted in insignificant lower values of total phenolics and total flavonoids compared with inorganically grown seeds. Adding multi-bioorganic to 50 or 75% compost treatments produced great enhancement effects on the total phenolic, flavonoid, protocatechuic acid, p-hydroxybenzoic acid, chlorogenic acid, caffeic acid, quercetin, genistein and daidzein contents compared with the other treatments. The most enhancement effect was exhibited for phenolic acids, quercetin and genistein. Addition of multi-bioorganic to 50% compost treatments resulted in 68 and 40% increases in quercetin and genistein, respectively, compared with the inorganic treatment, as well as 90 and 47% increases, respectively, compared with 50% compost alone. The highest values of antioxidant activity was determined in soyabean seeds grown under 50 and 75% compost, especially when mixed with bioorganic. Using either 50 or 75% compost in a mixture with bioorganic caused increases in antioxidant activity, varying between 25 and 60% when compared with other inorganic and compost alone treatments. Bioorganic fertilizers play a role in determining antioxidant activity and phenolic metabolites of soyabean seeds.
  • Authors:
    • Wilhelm, W. W.
    • Varvel, G. E.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 4
  • Year: 2008
  • Summary: Proposals promoting the use of massive amounts of crop residues and other lignocellulosic biomass for biofuel production have increased the need for evaluation of the sustainability of cropping practices and their effect on environment quality. Our objective was to evaluate the effects of crop rotation and N fertilizer management and their stover production characteristics on soil organic carbon (SOC) levels in a long-term high-yielding irrigated study in the western Corn Belt. An irrigated monoculture corn ( Zea mays L.), monoculture soybean [ Glycine max (L.) Merr.], and soybean-corn cropping systems study was initiated in 1991 on a uniform site in the Platte Valley near Shelton, NE. Soil samples were collected in 1991 before initiation of the study and in the spring of 2005 and analyzed for SOC. Significant differences in total SOC values were obtained between rotations and N rates at the 0- to 7.5- and 0- to 15-cm depths in 2005 and all total SOC values were equal to or greater than SOC values obtained in 1991. Residue production was greater than 6 Mg ha -1, a level that appears to be sufficient to maintain SOC levels, in all systems. Can residue amounts above this level be harvested sustainably for biofuel production in cropping systems similar to these? Though these results suggest that a portion of corn stover could be harvested without reducing SOC under the conditions of this investigation, the direct impact of stover removal remains to be evaluated.
  • Authors:
    • Zhu, D. W.
    • Jin, Z. Q.
  • Source: Acta Agronomica Sinica
  • Volume: 34
  • Issue: 9
  • Year: 2008
  • Summary: Nine scenarios of climatic change and climatic variability were generated in 19 sites in 3 agroecological zones in northeast China using the WGEN as a tool and based on the output of three general circulation models (GISS, GFDL, and UKMO GCMs), the local current daily weather data from 1961 to 2000 at each site, as well as on the three hypotheses on the increase in climatic variability in future. Four crop models (SOYGRO, CERES-Maize, CERES-Wheat, and CERES-Rice) were selected as the effect models and their parameter modification, validation and sensitivity analyses were carried out using the baseline weather, statistical yield data of the 4 crops and the local typical soil data. Finally, the potential impacts of changes in both climate and its variability on the food production in this regions with a doubling of CO 2 concentration doubled were assessed by running the effect models under both baseline and various (climatic change+climatic change variability) scenarios, and by comparing the outputs simulated. The results showed that the four effect models were available in the studied regions and can be used as a tool in climate impact study. Climate change would be favorable for soyabean and rice production in the region, especially in the northern cold zone and eastern wet zone, but unfavorable for both maize and spring wheat, where the simulated yields particularly maize yield, were significantly reduced under all the scenarios. With increasing of climatic variability, not only the yields were reduced compared with the control, but also the yield stabilities also decreased for the rainfed crops, such as soyabean, maize and spring wheat. However, there was no influence for the irrigated rice.
  • Authors:
    • Santini, J. B.
    • Vyn, T. J.
    • Faghihi, J.
    • Ferris, V. R.
    • Westphal, A.
    • Creech, J. E.
    • Johnson, W. G.
  • Source: Weed Science
  • Volume: 56
  • Issue: 1
  • Year: 2008
  • Summary: Certain winter annual weeds have been documented as alternative hosts to soybean cyst nematode (SCN), and infestations of such species have become common in no-till production fields in the Midwest. This research was conducted to determine the influence of herbicide- and cover-crop-based winter annual weed management systems and crop rotation on winter annual weed growth and seed production, SCN population density, and crop yield. Two crop rotations (continuous soyabean and soyabean-maize) and six winter annual weed management systems (a nontreated control, autumn and spring herbicide applications, spring-applied herbicide, autumn-applied herbicide, autumn-sown annual ryegrass, and autumn-sown winter wheat) were evaluated in no-tillage systems from autumn 2003 to 2006 at West Lafayette and Vincennes, Indiana. Autumn or spring herbicide treatments generally resulted in lower winter annual weed densities than cover crops. Densities of henbit and purple deadnettle increased over years in the cover crop systems but remained constant in the herbicide systems. Averaged over sites and years, winter annual weed densities were nearly 45% lower in the spring than the autumn due to winter mortality. Maize yield was reduced by the cover crops at West Lafayette but not Vincennes. Winter annual weed management system had no influence on soyabean yield. SCN population density was reduced by including maize in the crop sequence but was not influenced by winter annual weed management. The density of weedy host species of SCN in the experimental area was relatively low (less than 75 plants m -2) compared to densities that can be observed in production fields. The results suggest that inclusion of maize into a cropping sequence is a much more valuable SCN management tool than winter annual weed management. In addition, control of winter annual weeds, specifically for SCN management, may not be warranted in fields with low weed density.