• Authors:
    • Yang, L.
    • Yin, S.
    • Xia, L.
    • Yu, Y.
    • Wu, D.
  • Source: PEDOSPHERE
  • Volume: 21
  • Issue: 6
  • Year: 2011
  • Summary: In the Three Gorges Area of China, soil erosion and the resultant non-point source pollution and ecological degradation have endangered agricultural ecosystems and fresh water reservoirs. Although efforts have been undertaken to reduce soil and water losses from slope land used for citrus production, information on the effects of management practices on soil fertility indices is either limited or nonexistent. This study was conducted to compare the effects of 10 years of various management practices, citrus intercropped with white clover (WC), citrus mulched with straw (SM), citrus intercropped with contour hedgerows (CH), citrus orchard land with impermeable membrane (IM), and citrus intercropped with wheat ( Triticum aestivum) and peanut ( Arachris hypogaea) (WP), as treatments on soil fertility indices with that of the conventional citrus management (CM). Results showed that the soil organic carbon, total and available nitrogen, available potassium, and water-stable aggregate (>0.25 mm) contents at the 0-5 cm depth were higher for the WC and SM treatments than the CM treatment. There was also spatial variation in soil fertility along slopes of the WC and SM treatments. The soil total and available nitrogen, phosphorus, and potassium, and water-stable aggregate (>0.25 mm) contents at both the 0-5 and 5-20 cm depths were higher for the CH and IM treatments than the CM treatment. The average soil available nitrogen and available potassium contents were higher for the WP treatment than the CM treatment, but the WP treatment had little effect on the soil organic carbon, total nitrogen, and water-stable aggregate (>0.25 mm) contents. These suggested that white clover intercropping and straw mulching were the most effective approaches to improve soil fertility in citrus orchard land of the Three Gorges area.
  • Authors:
    • Smith, D.
    • Yang, W.
    • Chen, X.
    • Liu, W.
    • Zhang, J.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 27
  • Year: 2011
  • Summary: Production practice shows shaded soybean in wheat-maize-soybean; relay strip intercropping system has better tolerance to drought as compared with sole cropping soybean. Our researches are to understand the reasons through non-hydraulic root signals (nHRS), yield and the relationships among them. Pot experiments were conducted with two soybean cultivars, under shade of maize (LI) and normal irradiance (HI). nHRS were traced during manipulative progressive soil drying period at branching stage under good soil conditions (HW), water stress treatment (LW), in 2010. Well-watered (WW), light drought (LD), moderate drought (MD) and severe drought (SD) were applied in 2009. In response to soil drying, nHRS appeared earlier in Gongxuan No.1 (GX) than Gongqiudou 05-8 (GQ) under two irradiance treatments, but it disappeared earlier for GX than GQ under normal irradiance. GX exhibited a wider average soil water content threshold range (TR) of nHRS under low irradiance. Drought stress significantly decreased the shoot dry mass, root mass and grain yield (P
  • Authors:
    • Garcia, F.
    • Garcia, A.
    • Ernst, O.
    • Cano, J.
    • Bordoli, M.
    • Beux, L.
    • Bautes, C.
    • Barbazan, M.
    • Quincke, A.
  • Source: Agrociencia (Montevideo)
  • Volume: 15
  • Issue: 2
  • Year: 2011
  • Summary: The objectives of this study were to summarize the recent information generated in the country related to the potassium fertilization and find a tentative critical level of Potassium (K) in soil for various crops in Uruguay, using the most widely used K soil test. The data come from 50 K-response experiments in barley, wheat, corn, soybeans, sorghum, and sunflower, conducted by different working groups from 2004 to 2010, in soils with different texture and exchangeable K levels. The fertilizer rates ranged from 0 to 240 kg/ha of K 2O and in all cases the source of K was broadcasted KCl at planting date. Potassium fertilizer increased crop yield in 15 of 50 sites (Pr
  • Authors:
    • Fiorin, J.
    • Nicoloso, R.
    • Tornquist, C.
    • Amado, T.
    • Campos, B.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Soil C-CO 2 emissions are sensitive indicators of management system impacts on soil organic matter (SOM). The main soil C-CO 2 sources at the soil-plant interface are the decomposition of crop residues, SOM turnover, and respiration of roots and soil biota. The objectives of this study were to evaluate the impacts of tillage and cropping systems on long-term soil C-CO 2 emissions and their relationship with carbon (C) mineralization of crop residues. A long-term experiment was conducted in a Red Oxisol in Cruz Alta, RS, Brazil, with subtropical climate Cfa (Koppen classification), mean annual precipitation of 1,774 mm and mean annual temperature of 19.2degreesC. Treatments consisted of two tillage systems: (a) conventional tillage (CT) and (b) no tillage (NT) in combination with three cropping systems: (a) R0 - monoculture system (soybean/wheat), (b) R1 - winter crop rotation (soybean/wheat/soybean/black oat), and (c) R2 - intensive crop rotation (soybean/black oat/soybean/black oat+common vetch/maize/oilseed radish/wheat). The soil C-CO 2 efflux was measured every 14 days for two years (48 measurements), by trapping the CO 2 in an alkaline solution. The soil gravimetric moisture in the 0-0.05 m layer was determined concomitantly with the C-CO 2 efflux measurements. The crop residue C mineralization was evaluated with the mesh-bag method, with sampling 14, 28, 56, 84, 112, and 140 days after the beginning of the evaluation period for C measurements. Four C conservation indexes were used to assess the relation between C-CO 2 efflux and soil C stock and its compartments. The crop residue C mineralization fit an exponential model in time. For black oat, wheat and maize residues, C mineralization was higher in CT than NT, while for soybean it was similar. Soil moisture was higher in NT than CT, mainly in the second year of evaluation. There was no difference in tillage systems for annual average C-CO 2 emissions, but in some individual evaluations, differences between tillage systems were noticed for C-CO 2 evolution. Soil C-CO 2 effluxes followed a bi-modal pattern, with peaks in October/November and February/March. The highest emission was recorded in the summer and the lowest in the winter. The C-CO 2 effluxes were weakly correlated to air temperature and not correlated to soil moisture. Based on the soil C conservation indexes investigated, NT associated to intensive crop rotation was more C conserving than CT with monoculture.
  • Authors:
    • Castoldi, G.
    • Costa, L.
    • Steiner, F.
    • Costa, M.
    • Pivetta, L.
  • Source: Revista Ceres
  • Volume: 58
  • Issue: 2
  • Year: 2011
  • Summary: The use of animal manure combined with cover crops can provide sustainability to agricultural systems. Aiming to evaluate the effect of two farming systems and nutrient sources on the corn crop, an experiment was conducted on an Oxisol, in the municipality of Marechal Candido Rondon, Parana State, Brazil. The experiment was arranged in a randomized block design with treatments in a factorial scheme 2*3, consisting of two crop systems (succession wheat/corn and intercropping oat+vetch+turnip/corn) and three nutrient sources (mineral, organic and organic-mineral), with four replications. In June 2006, the wheat crop and the intercropping of cover crops were established. In October 2006, the corn was sowed on the two systems. Organic and organic-mineral fertilizations consisted of application of pig manure alone and combined with mineral fertilizer, respectively. Intercropping of oat, hairy vetch and wild radish produced adequate amount of biomass, showing its viability for providing soil cover during winter. Corn grown in rotation with wheat yielded the highest uptake of N and K and highest yield. Mineral fertilization gave higher N uptake and corn yield compared with the organic fertilizer and organic-mineral fertilizer based on pig manure.
  • Authors:
    • Vasseur, L.
    • Lotz, L.
    • You, M.
    • Lai, R.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 3
  • Year: 2011
  • Summary: The green peach aphid, Myzus persicae (Sulzer), is an insect pest that causes extensive damage to tobacco ( Nicotiana tabacum L.) in China. Field trials were conducted in 2008 and 2009 at Longyan in the Fujian Province (China) to evaluate the effects of garlic ( Allium sativum L.) as a deterrent to green peach aphids and other arthropods when intercropped in flue-cured tobacco fields. This study demonstrated that green peach aphids were affected by intercropping garlic in tobacco fields during the 2 yr studied. The appearance of green peach aphids in intercropped tobacco fields was delayed for approximately 7 d by the presence of garlic. Aphid abundance was reduced by 100% in intercropped fields compared with monocultures, especially when populations peaked (34.7-39.0% in 2008 and 42.0-47.2% in 2009). Other arthropod populations were not negatively affected by intercropping garlic. Species richness, diversity, and stability of the arthropod communities increased and the dominance concentration index decreased in the intercropped garlic fields. The tobacco mosaic viruses (cucumber mosaic virus, potato virus Y, tobacco etch virus, and tobacco ring-spot virus) transmitted by green peach aphids were decreased by 9.6 to 42.4% in 2008 and by 22.1 to 27.9% in 2009 by intercropping garlic in flue-cured tobacco fields. The net benefits of cropping flue-cured tobacco were also increased by 52.1 to 80.2% by intercropping garlic in the tobacco fields. Therefore, intercropping tobacco with garlic may be useful in deterring green peach aphids and in stabilizing arthropod communities in tobacco.
  • Authors:
    • Ventrella, D.
    • Giorgio, D.
    • Bovera, F.
    • Lestingi, A.
    • Tateo, A.
  • Source: Journal of Food Agriculture & Environment
  • Volume: 9
  • Issue: 1
  • Year: 2011
  • Summary: A field trial was conducted to evaluate the effects of tillage system and fertilizer N applied to the preceding gramineous rotational crop on horse bean ( Vicia faba L. minor) yield and N uptake, chemical composition and nutritive value. The study took place during the periods 2002-2003 and 2004-2005 within the framework of a long-term experiment started in 1990 and involving a 2-year rotation including triticale and horse bean. The experimental layout was a split-plot design with three replicates and four tillage systems in the main plots. Tillage treatments included conventional tillage (CT), two-layer tillage (TT), surface tillage (ST) and minimum tillage (MT). In the subplots, the three N fertilization rates, applied to the preceding triticale crop, were 0 kg ha -1 (N 0), 50 kg ha -1 (N 50) and 100 kg ha -1 (N 100). Over the whole experimental period, tillage system did not significantly influence horse bean seed yield, N uptake, crude protein content and 48-h in vitro true dry matter digestibility. In spite of many significant interactions among experimental variables, there were comparable results under the different tillage systems, in both the less favourable and more productive years. N fertilization, applied to the preceding gramineous crop, did not exert noteworthy effects on horse bean seed quantiqualitative parameters studied. Continuous reduced tillage management, such as two-layer, surface and minimum tillage, would represent a viable alternative to conventional tillage for horse bean production, under rainfed Mediterranean conditions. In addition to their nutritional significance, these results are of economic and environmental importance, given the interest in adopting reduced tillage systems to limit the risk of soil erosion and degradation. The rate of fertilizer N should be optimized as a function of the production and quality of the preceding cereal crop.
  • Authors:
    • Perim, L.
    • Castro, G.
    • Crusciol, C.
    • Marques, R.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 35
  • Issue: 2
  • Year: 2011
  • Summary: Lime and gypsum influence nutrient availability and uptake, as well as the content of organic acids in the aerial plant parts. These changes, quantified by plant analysis of soluble nutrients, may potentiate the effect of soil amendment, ensuring the sustainability of the no-tillage system. In this sense the effect of lime and gypsum surface application on the content of water-soluble nutrients in peanut and oat residues was evaluated. The experiment was conducted on an Oxisol in Botucatu (SP) in the growing seasons 2004/2005 and 2005/2006. It was arranged in a randomized block design in split plots with four replications, where lime rates represented the plots and presence or absence of gypsum application the subplots. Peanut was grown in summer and white oat in the winter in the entire experimental area. Gypsum applied to peanut increased soluble Ca only in the first season, due to the short period between product application and determination of soluble nutrient contents in the plant extract. Liming of peanut and oat increased soluble Ca, Mg, K contents, did not alter Cu content and reduced Zn, Mn and Fe contents in both years of cultivation. Gypsum on the other hand reduced the electrical conductivity of peanut (2004/2005 and 2005/2006) and white oat (2004/2005).
  • Authors:
    • Martiniello, P.
  • Source: European Journal of Agronomy
  • Volume: 35
  • Issue: 4
  • Year: 2011
  • Summary: Rotations experiment have been investigated from 1991 to 2008 under irrigated and rainfed condition in Mediterranean environment. The crops studied were: annual winter binary mixture (BM), perennial meadow (ME) and durum wheat (W) continuously rotated for 3 years and W rotated on itself for all period of experiment (CW). The forage rotations emphasized on the impact made on biochemical characteristics of topsoil and productivity of the crops. The 3 years continuous wheat rotation over forage crops assess the advantage of forage crops left in the soil on seed yield and on quality of kernel. The continuous wheat rotation (CW) reduced the soil biochemical parameters, seed yield and quality of kernel. The value of organic carbon, C/N and total nitrogen, under rainfed in comparison to the values present in the topsoil at the beginning of experiment were 6.4% and 2.48 higher and 11.2% lower in ME and lower 5.2% in organic carbon and 2.8% total nitrogen and 0.21 higher in C/N in BM. The agronomic advantages allowed by forage rotations expire their effect after 3 years of continuous wheat. Yearly yield W gain under rainfed was 11.3 kg (ha yr) -1 in BM and 62 kg (ha yr) -1 in ME. The qualitative traits of wheat kernel rotated on forage were higher than those of continuous wheat CW. Results of biochemical characteristics obtained at the end of experiment evidenced that W after BM and ME rotations sustained, under irrigated and rainfed condition, the content of organic carbon and total nitrogen and C/N in the topsoil of the cropping system while continuously CW allowed strong impact of the parameter values present at beginning of experiment (organic carbon, total nitrogen and C/N was reduced under rainfed by 23.5%, 18.2 and 0.32 and 30.3%, 15.4% and 1.72 under irrigated, respectively).
  • Authors:
    • Bow, J.
    • Muir, J.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 4
  • Year: 2011
  • Summary: 'Tifton 85' bermudagrass [ Cynodon dactylon L. (Pers.) * C. transvaalensis Burt Davy] is a warm-season forage used on southeastern U.S. dairy concentrated animal feeding operations (CAFO). Cool-season annual forages need to be identified that can be overseeded into Tifton 85 and remove the greatest quantity of P or N while minimizing suppression of bermudagrass spring regrowth. During 3 yr we overseeded six grass, five legume, and two Brassica spp. on a dairy CAFO Tifton 85 field on a Windthorst fine sandy loam (fine, mixed, active, thermic Udic Paleustalf) containing 83 mg plant-available P kg -1 soil. Hairy vetch ( Vicia villosa Roth.), barley ( Hordium vulgare L.), oat ( Avena sativa L.), and rye ( Secale cereale L.) yielded the most (entry * year interaction P