• Authors:
    • Smith, J. P.
    • Smith, M. K.
    • Stirling, G. R.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: Ginger (Zingiber officinale) production is facing increasing disease and pest pressure and declining yield with continuing intensive cultivation practices. A four year experiment was established in south-eastern Queensland on a red ferrosol that had a long (>60 years) history of ginger farming. Minimal tillage and organic amendments were compared with conventional practice that involved frequent tillage and soil fumigation using 1,3-dichloropropene (Telone (R)). Ginger crops were grown in the second and fourth year of the experiment, following an annual rotation with different cover crops including oats (Avena sativa), Brassica spp., soybean (Glycine max) and forage sorghum (Sorghum bicolour X S. sudanese). A pasture ley of Pangola grass (Digitaria eriantha subsp. pentzii) provided a treatment continuum from major to minor disruption in the soil's physical fertility and biological communities, and was therefore only planted to ginger in the fourth year of the experiment. Ginger seed-pieces (sections of the rhizome used for planting) were planted into both tilled and untilled beds using a double disc opener on a specially designed ginger planter. Rhizome yield in the final year was greatest (74.2 t/ha) and losses to pathogens (Pythium myriotylum and Fusarium oxysporum f. sp. zingiberi) minimal (7.0%) in the pasture ley that had been cultivated prior to planting ginger. Furthermore, the minimum-tilled cover cropped treatment, which likewise had been cultivated prior to planting ginger, yielded well (62.0 t/ha), with few losses (5.0%) from rhizome rots. Conversely the fumigated treatment had the highest losses (35.9%) due to Pythium Soft Rot and lowest yields (20.2 t/ha). Minimum-tilled plantings of ginger, however, resulted in poor yields (30.9-43.1 t/ha) but had acceptable levels of disease. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Hyde, J.
    • Mortensen, D. A.
    • Barbercheck, M. E.
    • Smith, R. G.
    • Hulting, A. G.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 1
  • Year: 2011
  • Summary: In the mid-Atlantic region, the demand for organic dairy has provided incentives for farmers to transition their land to organic feed grain production. At the same time, interest in minimum-tillage organic production is growing. Two field experiments were conducted to assess the effects of a first year cover crop and tillage system on weed populations, cash crop yield, and net returns over the 3-yr transition period in a cover crop-soybean (Glycine max (L.) Merr.)-corn (Zea mays L.) feed grain rotation. The cover crop treatments were rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) (hereaft er RYE) and timothy (Phleum pratense L.)-red clover (Trifolium pratense L.) (hereaft er TIM). Tillage system treatments were moldboard plow (full tillage, FT) and chisel plow (minimum tillage, MT). Across both experiments, soybean yields ranged from 1190 to 3721 kg ha(-1). Corn grain yields were affected by tillage in the first experiment only, and were 59% higher in FT (9370 kg ha(-1)) compared to MT (5906 kg ha(-1)). Weed abundance was primarily affected by tillage, with densities in corn being 244% higher in MT compared to FT. Cumulative net returns in the first experiment were profit-generating in systems where TIM was the initial cover crop (mean = U.S. $ 317 ha(-1)). Mean cumulative net returns were positive in three of the four treatment combinations in the second experiment (U.S. $ 74-299 ha(-1)). Improved strategies for minimizing the costs associated with fertilization and management of weeds in minimal tillage will be necessary to improve the profitability and sustainability of reduced-tillage organic systems.
  • 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:
    • 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:
    • Karanisa, T.
    • Gerhards, R.
    • Brust, J.
    • Ruff, L.
    • Kipp, A.
  • Source: GESUNDE PFLANZEN
  • Volume: 63
  • Issue: 4
  • Year: 2011
  • Summary: Cover crops and under-sown crops have often been reported to have a positive impact on soil structure, soil living organisms and soil fertility. In many studies it was shown that they suppress weed populations. However, the percentage of winter annual cereals in European cropping system has strongly increased, which consequently reduced the time for growing cover crops. In this study, it was investigated if cover crops and under-sown have the capacity to reduce weed infestations also in rotations with a high percentage of winter annual cereals. Three field trials were conducted using at the University of Hohenheim from 2008 until 2010. Trifolium repens and Lolium perenne reduced weed density and weed biomass in Triticum aestivum and Triticum spelta, when they were sown as under-sown crops. Both under-sown crops had no negative effect on grain yield. Until 14 days after harvest, the under-sown crops developed a dense plant canopy. In the third experiment, Sinapis alba, Phacelia tanacetifolia, Avena strigosa and a mixture of Trifolium alexandrinum, Vicia sativa, Fagopyrum tataricum and Guizotia abyssinica were sown directly after harvest of winter wheat. Most of the cover crops emerged after few days and significantly reduced the density and biomass of emerging weeds. Sinapis alba resulted in a 93% reduction of above-ground weed biomass. Avena strigosa reduced root-biomass of weed by 97% and weed density by 90%. In order to achieve a significant weed suppression, cover crops need to emerged quickly and grow rapidly until the soil has been covered. The results of this study underline the potential of under-sown crops and cover-crops to support a sustainable and environmental friendly cropping system.
  • Authors:
    • Klein, D.
    • Dech, S.
    • Colditz, R. R.
    • Conrad, C.
    • Vlek, P. L. G.
  • Source: International Journal of Remote Sensing
  • Volume: 32
  • Issue: 23
  • Year: 2011
  • Summary: Crop cover and crop rotation mapping is an important and still evolving field in remote sensing science for which robust and highly automated processing chains are required. This study presents an improved mapping procedure for crop rotations of irrigated areas in Central Asia by using classification and regression trees (CARTs) applied to transformations of 250 m Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) time series. The time series were divided into several temporal segments, from which metrics were derived as input features for classification. This temporal aggregation was applied to suppress within-class temporal variability. Various lengths of temporal segments were tested for their potential to increase classification accuracy. In addition, tests of enhancing the classification accuracy were done by combining different classification results using the majority rule for voting. These different processing strategies were applied to four annual time series (2004-2007) of the Khorezm region, where 270 000 ha of irrigated land is dominated by rotations of cotton, wheat and rice. Improved classification results were obtained for CARTs applied to metrics derived from a mixture of different segment lengths. The sole use of either long or short temporal segments was inferior. CART prioritized segments representing active phases of the phenological development. The best result, the optimized segment-based approach, achieved an overall accuracy between 83 and 85% for classifications between 2004 and 2007; in particular, the small range demonstrated the robustness regarding inter-annual variations. These accuracies exceeded those of the original time series without temporal segmentation by 6-7%. With some adjustments to other crops and field heterogeneity influencing the usefulness of a respective sensor, the approach can be applied to other irrigation systems in Central Asia.
  • Authors:
    • Lucas, P.
    • Montfort, F.
    • Jeuffroy, M.-H.
    • Goulevant, G.
    • Reynaud, A.
    • Jacquet, F.
    • De Cara, S.
  • Source: Environmental Modeling & Assessment
  • Volume: 16
  • Issue: 1
  • Year: 2011
  • Summary: This paper addresses the question of summer cover-crop adoption by farmers in presence of a risk of yield loss due to take-all disease and climate variability. To analyze the public incentives needed to encourage farmers to adopt summer cover crops as a means of reducing N leaching, we combine outputs from an economic, an epidemiological and an agronomic model. The economic model is a simple model of choice under risk. The farmer is assumed to choose among a range of summer fallow managements and input uses on the basis of the expected utility criterion (HARA assumption) in presence of both climate and take-all risks. The epidemiological model proposed by Enna
  • Authors:
    • Maldaner, G. L.
    • Spera, S. T.
    • Fontaneli, R. S.
    • dos Santos, H. P.
  • 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:
    • Rao, I. M.
    • Schmidt, A.
    • van der Hoek, R.
    • Bernasconi, S. M.
    • Frossard, E.
    • Douxchamps, S.
    • Oberson, A.
  • Source: Plant and Soil
  • Volume: 341
  • Issue: 1-2
  • Year: 2011
  • Summary: The integration of multipurpose legumes into low-input tropical agricultural systems is needed because they are a nitrogen (N) input through symbiotic fixation. The drought-tolerant cover legume canavalia (Canavalia brasiliensis) has been introduced for use either as forage or as a green manure into the crop-livestock system of the Nicaraguan hillsides. To evaluate its impact on the subsequent maize crop, an in-depth study on N dynamics in the soil-plant system was conducted. Microplots were installed in a 6-year old field experiment with maize-canavalia rotation. Direct and indirect (15)N-labelling techniques were used to determine N uptake by maize from canavalia residues and canavalia-fed cows' manure compared to mineral fertilizer. Litter bags were used to determine the N release from canavalia residues. The incorporation of N from the amendment into different soil N pools (total N, mineral N, microbial biomass) was followed during the maize cropping season. Maize took up an average of 13.3 g N m(-2), within which 1.0 g N m(-2) was from canavalia residues and 2.6 g N m(-2) was from mineral fertilizer, corresponding to an amendment N recovery of 12% and 32%, respectively. Recoveries in maize would probably be higher at a site with lower soil available N content. Most of the amendment N remained in the soil. Mineral N and microbial N were composed mainly of N derived from the soil. Combined total (15)N recovery in maize and soil at harvest was highest for the canavalia residue treatment with 98% recovery, followed by the mineral fertilizer treatment with 83% recovery. Despite similar initial enrichment of soil microbial and mineral N pools, the indirect labelling technique failed to assess the N fertilizer value of mineral and organic amendments due to a high N mineralization from the soil organic matter.
  • Authors:
    • Wokocha, C. C.
    • Eludoyin, O. S.
  • Source: Asian Journal of Agricultural Sciences
  • Volume: 3
  • Issue: 2
  • Year: 2011
  • Summary: The present study evaluated the impacts of maize cultivation on soil properties under the continuous monocropping system of farming in South-western Nigeria. Soil samples were collected from both cultivated maize plot and less disturbed secondary forest, both lying contiguous to each other. Laboratory analysis was carried out to determine the levels of particle size composition, porosity, bulk density; and concentrations of Cations Exchange Capacity (CEC), Exchangeable Sodium (Na), Exchangeable Calcium (Ca), Exchangeable Magnesium (Mg), Available Phosphorous (P), Soil pH, Exchangeable Acidity, Organic Carbon (C) and Nitrogen (N). The mean of each of these soil properties was used for comparison and t-test was also used to determine the significant difference that exists in each soil property. The result shows that the level of C, N and porosity were higher in soils under forest than soils under maize. However, there was no significant difference in Exchangeable Acidity, Mg, Soil pH and Ca in the two land use types. Nevertheless, the concentrations of Na and K were higher in the cultivated soils while P and Ca were lower in the cultivated soils. The particle size composition was predominantly sandy. Planting of cover crops, mixed cropping and mulching among others were suggested as ways to minimize erosion and leaching so that fertility can be restored and maintained.