• Authors:
    • Duarte, G.
    • Diaz-Zorita, M.
    • Barraco, M.
  • Source: Wheat Production in Stressed Environments Developments in Plant Breeding
  • Volume: 12
  • Year: 2007
  • Summary: Wheat ( Triticum aestivum L.) grain yields under no-till production systems have been shown to be reduced in the presence of maize ( Zea mays L.) residues. It has been suggested that sowing a greater density of wheat seeds or removing maize residues from the planting rows contributes to avoid this problem. However, the causal factors and the mechanism that produce reductions in wheat yields are no clearly defined. Our objective was to determine the effects of different volumes of maize or soybean [ Glycine max (L.) Merrill] residues on no-tillage wheat establishment and production under field conditions on a Typic Hapludoll from the Pampas region of Argentina. The study was performed during the 2002, the 2003 and the 2004 growing seasons. Two treatments [residue volume (0, 4, 8 and 16 Mg ha -1) and crop residue (maize and soybean)] were imposed after sowing wheat at low and high plant densities, (301 and 396 seed ha -1, respectively). The previous crop was sunflower ( Helianthus annus L.) and the residues were applied on the soil surface immediately after planting and fertilizing with 125 kg ha -1 of Nitrogen. Independently of the quality of the residues and the sowing density, wheat plants m -2, spikes m -2 and grain yields ha -1 decreased when residue volume increased. In general, lower soil temperatures values and variability were observed when increasing the volume of residues. The presence of large amounts of maize or soybean residues causes the reduction in no-tillage wheat productivity (plant stand and numbers of spikes). However, only maize residues causes significant reductions in grain yields, independently of the seeding rate. The absence of significant differences in soil temperature measurements between residues allows us to think that the effects on surface soil temperature are not the main factor explaining the reduction in wheat grain yields in the presence of maize residues. Increasing the seeding rate can contribute to ameliorate the grain yield reduction in the presence of maize residues but further research is required for explaining the reasons for the behavior of the crop.
  • Authors:
    • Mentreddy, R. S.
    • Cebert, E.
    • Kumar, S.
    • Bishnoi, U. R.
  • Source: World Journal of Agricultural Sciences
  • Volume: 3
  • Issue: 3
  • Year: 2007
  • Summary: In the southeastern USA, winter rape in addition to winter wheat can become another commercial crop with benefits such as breaking of disease and insect cycles caused by continuous wheat cropping. Information on agronomic production practices and comparative profitability of rape and wheat for the southeastern USA is lacking. Therefore, from 1998 to 2005, a series of field experiments were conducted on rape to determine the optimum planting date, seeding, nitrogen and sulfur rates, rotation suitability with summer crops and comparative economic value to winter wheat. Results from three planting dates, three seeding rates and four nitrogen rates experiments showed that rape planted in early October produced significantly higher seed yield (3204 kg/ha) than from mid to late October 10-15 (2362 and 2058 kg/ha) plantings. The seeding rate of 6.0 kg/ha and 180 kg N/ha gave the highest (3779 kg/ha) seed yield. Rape response to sulfur application was significant and highest seed yield (3259 kg/ha) was obtained with 30 kg S/ha along with 228 kg N/ha. As a rotation crop after soyabean and maize, rape gave significantly higher yields of 3129 and 2938 kg/ha, respectively, than when planted after cotton (2521 kg/ha) or grain sorghum (2650 kg/ha). Both winter rape and wheat produced similar yields of 2.6 and 2.9 t/ha, respectively. As grain crop, canola with its higher price fetched $220/ha compared to $109/ha from wheat, however, this profitability is almost equal when income from wheat straw was added to that from grain.
  • Authors:
    • Jamwal, J. S.
  • Source: Indian Journal of Agronomy
  • Volume: 51
  • Issue: 1
  • Year: 2006
  • Summary: A field experiment was conducted during rainy ( kharif) and winter ( rabi) seasons of 1998-99 and 1999-2000 at Dryland Research Substation, Rakh Dhiansar, Bari-Brahmana, Jammu and Kashmir, India, to evaluate the residual effect of integrated nutrient management in maize ( Zea mays cv. GS 2) on succeeding Gobhi sarson ( Brassica napus [ B. campestris var. sarson] cv. GSL 2) and chickpea ( Cicer arietinum cv. PBG 1). Application of recommended dose of NPK (60:40:20 kg/ha)+20 kg ZnSO 4/ha during kharif significantly increased the grain yield of maize as well as the succeeding crops of Gobhi sarson and chickpea. Application of farmyard manure (FYM) significantly increased the available N, P and K status of the soil after maize harvest. Available P status of the soil after the harvest of Gobhi sarson and chickpea also increased significantly due to the residual effect of FYM and fertility levels.
  • Authors:
    • Bali, S. V.
    • Singh, B.
    • Lehria, S. K.
  • Source: Short Rotation Forestry for Industrial and Rural Development
  • Year: 2006
  • Summary: A field experiment was conducted at Rakh Dhiansar during Kharif 1995 and 1996 and Rabi 1995-96 and 1996-97 under dryland conditions of Jammu (J&K). The results based on growth, yield attributes and yield revealed that application of 15 t ha -1 of subabul leaves as basal+25% N recorded maize (var. Local) yield of 45.22 q ha -1, which was significantly higher than the recommended dose of fertilizers and it was at par with 15 t ha -1 of subabul leaves as basal only, yielding 45.06 q ha -1. The residual effect of green leaf manuring on wheat (var. PBW-175) revealed that growth, reproductive and yield attributing characters were also influenced positively. By using this material, 50-75% N can be saved by the small and marginal farmers of the dryland region.
  • Authors:
    • Shivani
    • Mishra, S.
    • Singh, V.
    • Sanjeev, K.
  • Source: Indian Journal of Agricultural Sciences
  • Volume: 76
  • Issue: 9
  • Year: 2006
  • Summary: A field experiment was conducted in Bihar, India during the winter of 2002-04 to determine the effects of irrigation and tillage on the soil-water-plant relationship and productivity of maize cv. Deoki. The treatments included disc ploughing + 2 harrowing + planking (T1), 2 cultivator + planking (T2), rotavator (T3) and zero-till planter (T4), in combination with 3 irrigations during the pre-knee height of the crop (30 days after sowing (DAS)), knee height and silking stages (I1), I1 + irrigation during the milking stage (I2), irrigation during the pre-knee height, knee-height, tasseling, milking and grain filling stages (I3) and irrigation during the pre-knee height, knee height, tassel initiation, silking, milking and grain filling stages (I4). The physical properties of the soil of rotavator-tilled plots recorded higher bulk density (1.33 and 1.30 mg/m 3), soil strength (2.10 and 2.05 MPa), infiltration rate (0.420 and 0.432 cm/ha) and porosity (49.81 and 50.94%) during 2002-03 and 2003-04, respectively. Plant height (189.33 and 190.07 cm), leaf area index (2.673 and 2.728) dry matter accumulation (369.77 and 392.78 g) and relative leaf water content (94.61 and 93.36%) were highest with rotavator tilling during 2002-03 and 2003-04. Plants receiving 5-6 irrigations exhibited superior crop yield and yield attributes. Rotavator-tilled maize showed higher water expense efficiency compared to plants under different tillage systems. Rotavator tilled maize irrigated 5-6 times recorded the highest grain yield (5831 and 5960kg/ha) and net returns (Rs. 16 173 and Rs. 17 493) during 2002-03 and 2003-04, respectively.
  • Authors:
    • Pitts, T.
    • Atwood, J. D.
    • Williams, J. R.
    • Potter, S. R.
    • Wang, X.
  • Source: Transactions of the ASABE
  • Volume: 49
  • Issue: 3
  • Year: 2006
  • Summary: Sensitivity analysis for mathematical simulation models is helpful in identifying influential parameters for model outputs. Representative sets of APEX (Agricultural Policy/Environmental eXtender) model data from across the U.S. were used for sensitivity analysis to identify influential parameters for APEX outputs of crop grain yields, runoff/water yield, water and wind erosion, nutrient loss, and soil carbon change for a national assessment project: the Conservation Effects Assessment Project (CEAP). The analysis was based on global sensitivity analysis techniques. A test case, randomly selected from the representative sets of APEX model data, was first analyzed using both the variance-based sensitivity analysis technique and the enhanced Morris method. The analysis confirmed the reliability of the enhanced Morris measure in screening subsets of influential and non-influential parameters. Therefore, the enhanced Morris method was used for the national assessment, where the cost of applying variance-based techniques would be excessive. Although sensitivities are dynamic in both temporal and spatial dimensions, the very influential parameters (ranking 1st and 2nd) appear very influential in most cases. Statistical analyses identified that the NRCS curve number index coefficient is very influential for runoff and water-related output variables, such as soil loss by water, N and P losses in runoff. The Hargreaves PET equation exponent, moisture fraction required for seed germination, RUSLE C factor coefficient, and the potential heat units are influential for more than two APEX outputs studied.
  • Authors:
    • Macdonald, B. C. T.
    • Bryant, G.
    • White, I.
    • Moody, P.
    • Stainlay, W.
    • Dalal, R. C.
    • Denmead, O. T.
  • Source: Proceedings of the Australian Society of Sugar Cane Technologists
  • Volume: 28
  • Year: 2006
  • Authors:
    • Grace, P. R.
    • Post, W. M.
    • Hennessy, K.
  • Source: Carbon Balance and Management
  • Volume: 1
  • Year: 2006
  • Authors:
    • Acciaresi, H. A.
    • Zuluaga, M. S.
  • Source: Planta Daninha
  • Volume: 24
  • Issue: 2
  • Year: 2006
  • Summary: The use of narrow plant spacing in corn (Zea mays) has been suggested as a technological alternative to obtain grain yield increases, due to a better use of resources. The regular pattern could diminish intraspecific competition while favoring interspecific competition with weeds. The objective of this study was to analyze the effect of corn row spacing on weed aboveground biomass and corn grain yield. Field experiments were conducted during 2002/ 2003 and 2003/2004 growing seasons. Three corn hybrids with two-row width (0.70 and 0.35 m) were tested. A greater photosynthetic photon flux density (PPFD) interception with a lower weed aboveground dry matter in narrow row arrangement was obtained. Corn grain yield was greater in the narrow row arrangement than in the wide row spacing. This increase in grain yield was related to a better resource use that allows for a reduced interspecific competition. The use of reduced spatial arrangement appeared to be an interesting alternative to increase both the grain yield potential and corn suppressive ability against weeds in corn dryland production systems.
  • Authors:
    • Bona, F. D. de
    • Bayer, C.
    • Bergamaschi, H.
    • Dieckow, J.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 30
  • Issue: 5
  • Year: 2006
  • Summary: The effect of irrigation on soil C stocks is a result of the balance between the effect of this practice on C input through crop residues and of C losses through microbial decomposition of soil organic matter (SOM). This study assessed the influence of sprinkler irrigation on SOM dynamics and on the total C stocks in a subtropical Acrisol under no-tillage (NT) and conventional tillage (CT) in a long-term experiment (8 years) in Universidade Federal do Rio Grande do Sul, RS, Brazil. Irrigation increased the C addition (about 8 kg C ha -1 yr -1 per mm precipitation) in both tillage systems, but this was not enough to increase the soil C stocks (0-20.0 cm) because irrigation also increased the decomposition rate of SOM by 19% in the CT soil and by 15% in NT soil. In the top layers (0-2.5 and 2.5-5.0 cm), the C concentration was higher in the NT than in CT soil, while the opposite trend was observed in the deepest layer (10.0-20.0 cm). Thus, the total C stocks in the whole 0-20.0 cm layer did not differ between tillage systems. The oat residue decomposition rate in NT soil increased with irrigation, which corroborates the higher SOM decomposition rates estimated for the irrigated soil. Based on these results, it becomes clear that the establishment of a high input cropping system able to counterbalance the higher SOM decomposition rates is a crucial point in the maintenance or improvement of soil C stocks in irrigated tropical and subtropical croplands.