• Authors:
    • Cui, S.
    • Chang, X.
    • Xu, B.
    • Zhu, X.
    • Luo, C.
    • Wang, S.
    • Duan, J.
    • Zhang, Z.
  • Source: Plant and Soil
  • Volume: 362
  • Issue: 1-2
  • Year: 2013
  • Summary: Few studies have investigated the effect of nitrogen (N) fertilizer on ecosystem respiration (Re) under mixed legume and grass pastures sown at different seeding ratios,and data are almost entirely lacking for alpine meadow of the Tibetan Plateau. Our aim was to test the hypothesis that although a combination of legumes with grass and N fertilizer increases Re the combination decreases Re intensity (i.e. Re per unit of aboveground biomass) due to greater increases in aboveground biomass compared to increases in Re. This hypothesis was tested using different seeding ratios of common vetch (Vicia sativa L.) and oat (Avena sativa L.) with and without N fertilizer on the Tibetan plateau in 2009 and 2010. Re was measured using a static closed opaque chamber. Re intensity was estimated as the ratio of seasonal average Re during the growing season to aboveground biomass. Compared with common vetch monoculture pasture, mixed legume-grass pastures only significantly decreased Re intensity (with a decrease of about 75 %-87 %) in the drought year 2009 due to greater increases in aboveground biomass compared to increases in Re. There were no significant differences in Re and Re intensity among different seeding ratios of oat and common vetch in either year. N fertilizer significantly decreased Re intensity for common vetch monoculture pasture by 24.5 % in 2009 and 69.5 % in 2010 although it did not significantly affect plant production and Re. From the perspective of forage yield and Re, planting mixed legume-grass pastures without N fertilizer is a preferable way to balance the twin objectives of forage production and mitigation of atmospheric greenhouse gas emissions in alpine regions.
  • Authors:
    • Huffman, T.
    • Coote, D. R.
    • Green, M.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.
  • Authors:
    • Huffman, T.
    • Green, M.
    • Coote, D.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.
  • Authors:
    • Penha, L.
    • Khatounian, C.
    • Fonseca, I.
  • Source: Planta Daninha
  • Volume: 30
  • Issue: 1
  • Year: 2012
  • Summary: Weed control has always been an important issue in agriculture. With the advent of no-till systems, soil erosion was reduced but herbicide use was increased. Organic no-till systems try to adjust reduced erosion to the no use of herbicides. Nevertheless, this adjustment is limited by the cost of mechanical weed control. This cost may be reduced by improved cultural weed control with cover crops mulches. In this paper we report a study on the application of compost manure on an oats winter cover crop, preceding soybean, instead of on the soybean summer crop. Treatments comprised a control without compost manure, and compost manure doses of 4 and 8 Mg ha -1 applied either on oats in winter or soybean in summer, organized in a randomized block design, with five replications. In summer, plots were split into weed-controlled or not controlled subplots. The timing of application and the manure doses did not affect the oats biomass or the soybean performance. However, in summer, without water stress, the application of manure at 8 Mg ha -1 directly on soybean has reduced weed biomass in this crop.
  • Authors:
    • Pacheco, C.
    • Martelli, I.
    • Schinor, E.
    • Rossetto, M.
    • Azevedo, F.
  • Source: REVISTA BRASILEIRA DE FRUTICULTURA
  • Volume: 34
  • Issue: 1
  • Year: 2012
  • Summary: The inter-row management of citrus orchards has undergone major changes in recent years. Thus, this study aimed to evaluate the effect of winter cover crops and rotary mower in sweet orange 'Pera' production. The experiment was conducted in two seasons (2007/2008 and 2008/2009), in a split plot design, where at the plots three species of winter cover crops (oat, lupine and radish) were sown in April and in sub-plots it was used two types of rotary mower (conventional and ecological). Natural vegetation (NV) and NV+herbicide ( glyphosate) in the total area were the standard treatments of the experiment. In July (2007 and 2008) it was measured the mass of fresh and dry mass of each treatment and also after mowing. To calculate the production in August (2007 and 2008) the fruit were harvested and weighted and later it was obtained the efficiency of production. The treatments with winter cover crops showed greater production of fresh and dry mass and the use of ecological rotary mower released amount of plant material significantly higher under the canopy of sweet orange 'Pera' plants. In two seasons, higher production and efficiency of fruit production occurred in plots using the ecological rotary mower. Only lupines increased the efficiency of production of sweet orange 'Pera' in 2009. Thus, it can be concluded that the use of ecological rotary mower increases the production of sweet orange 'Pera'.
  • Authors:
    • Tortosa, F.
    • Villafuerte, R.
    • Barrio, I.
  • Source: Wildlife Biology
  • Volume: 18
  • Issue: 1
  • Year: 2012
  • Summary: Damage caused by wildlife foraging can lead to significant agricultural losses and the problem can be further complicated if the damage-inducing animal is a valuable resource in its own right. Provision of alternative food sources such as cover crops might be a means of reducing the damage which appears to be linked to scarcity of alternative foods in intensively-managed agroecosystems. Cover crops may provide other benefits to agroecosystems, i.e. preventing soil erosion but can potentially have some undesired consequences, i.e. water competition with the cash crop. In our study, we tested the effectiveness of cover crops in reducing the damage caused by foraging European rabbit Oryctolagus cuniculus to vineyards in a semi-arid agroecosystem in southern Spain. Experimental treatments consisted of a combination of the presence/absence of sown cover crops (70% oat Avena sativa and 30% garden vetch Vicia sativa) with/without rabbit exclusion. In the 2009 growing season, we assessed rabbit-induced damage using a browsing index on vine shoots, rabbit use of plots was estimated based on faecal pellet counts and grapevine yield was measured at harvest. Rabbits ate the cover crops, and rabbit use was highest in the plots sown with the oat and vetch cover crop. However, the effect of the presence of the cover crop on the amount of damage caused by rabbits was limited and, moreover, the presence of the cover crop had a negative effect on grapevine yield. Exclosure fences effectively reduced rabbit damage by keeping rabbit densities close to zero, but even a low rabbit number (~1 rabbit/ha) can cause significant damage. Although cover crops provided rabbitswith an alternative food source, they acted as attractants for rabbits and were not effective in reducing the damage caused to vineyards by higher rabbit numbers. Therefore, adding cover crops might not be an effective measure in controlling rabbit-induced damage in semi-arid wine-growing regions.
  • Authors:
    • Gerhards, R.
    • Brust, J.
  • Source: Julius-Kuhn-Archiv
  • Volume: 1
  • Issue: 434
  • Year: 2012
  • Summary: Lopsided oat ( Avena strigosa) has been cultivated for many years, especially in Brazil, as a summer annual cover crop. Experiments were conducted in Stuttgart-Hohenheim in 2010 to estimate the capability of lopsided oat, yellow mustard ( Sinapis alba), phacelia ( Phacelia tanacetifolia) and a cover crop mixture to suppress weeds and volunteer wheat. A pot experiment was conducted to analyze the emergence and growth of the different cover crop species. Twelve weeks after planting, lopsided oat produced 20.7 dt/ha of shoot- and 5.5 dt/ha of root dry matter. A field experiment was established in the summer after harvest of winter wheat. The soil was cultivated with a disc harrow and the cover crops were sown one day later. At four week intervals, the plant density and dry matter of cover crops, weeds and volunteer wheat were determined. Twelve weeks after planting, lopsided oat produced 17.8 dt/ha shoot- and 6.2 dt/ha root dry matter. In the lopsided oat plots, shoot dry matter of weeds and volunteer wheat were reduced by 98% compared with control plots without cover crops. This was the highest weed reduction of all cover crops studied. The root dry matter of weeds and volunteer wheat was reduced by 55% to 97% in all cover crops, compared to the control plots. Lopsided oat reduced the plant density of weeds and volunteer wheat. While there were 54.5 plants/m 2 in the control plots, only 5.5 plants/m 2 were counted in the lopsided oat plots. The results showed that lopsided oat has a high potential for suppression of weeds and volunteer wheat in autumn. It also enlarges the number of cultivated cover crops in Central Europe.
  • Authors:
    • Tunali, M.
    • Carpici, E.
  • Source: Journal of Food Agriculture and Environment
  • Volume: 10
  • Issue: 2 part 2
  • Year: 2012
  • Summary: The current research was conducted to evaluate the forage yield and quality of stands of common vetch ( Vicia sativa L.) in various combinations with annual cereals such as oat ( Avena sativa L.), barley ( Hordeum vulgare L.) and wheat ( Triticum aestivum L.). Mixture rates were formulated using three combinations of common vetch-cereal (75:25, 50:50 and 25:75) under rainfed conditions in the southern Marmara Region, Turkey, during the 2009-2010 and 2010-2011 growing seasons. The field trials were arranged in a randomized block design with three replications. The averages of the two-year findings indicated that the highest dry matter was determined at pure oat stands, followed by common vetch-oat mixtures at ratios of 50:50 and 75:25. The highest crude protein yield was obtained from pure common vetch and common vetch-oat (75:25) stands. A common vetch-oat mixture at 75:25 can be recommended for experimental and similar ecologies because of its higher dry matter and crude protein yields.
  • Authors:
    • Valaci, F.
    • Andrade, L.
    • Fonseca, G.
    • Andrade, M.
    • Carvalho, G.
    • Carvalho, W.
    • Oliveira, D.
  • Source: Revista Brasileira de Biociencias
  • Volume: 10
  • Issue: 1
  • Year: 2012
  • Summary: This study aimed at evaluating the allelopathic effect of species used as cover crops in no-tillage system on common bean crop. It was conducted in the greenhouse and at the Seed Analysis Laboratory in the Agricultural Department of the Federal University of Lavras, Brazil. The cover crop species used in the experiment were sunn hemp, jack bean, pigeon pea, black oat, sorghum and millet, with and without intercropping, with their straws collected at the early grain filling stage. The aqueous extracts of 5% and 10% (w/v) obtained from those straws were placed in plastic boxes (Gerbox-type) containing common bean seeds. The straws were also laid on the substrate surface sown with common bean in plastic pots and installed in the greenhouse for chemical and physical effects evaluation of the cover crops. Considering most of the variables studied, it was not verified any damage by either using of mulch or by applying allelopathic extracts. When used as mulch or when applied as aqueous extracts, residues from the intercropping between sunn hemp and sorghum positively affected the common bean plant, benefiting its initial growth.
  • Authors:
    • Pauletti, V.
    • Favaretto, N.
    • Molin, R.
    • Mellek, J. E.
    • Dieckow, J.
    • Da-Silva, V. L.
    • Vezzani, F. M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 3
  • Year: 2012
  • Summary: The quality of no-tillage systems depends on an adequate soil management that promotes soil structure improvements. This is associated to the cropping system adopted. This study investigated the effect of long-term no-tillage systems (18 years) on the structural quality of a sandy-clay to clay Oxisol (Latossolo Vermelho) in the region of Campos Gerais, Parana, Brazil. Five cropping systems were assessed: wheat-soybean [Wt-So], black oat-maize-wheat-soybean [Ot-Mz-Wt-So], vetch-maize-wheat-soybean [Vt-Mz-Wt-So], ryegrass-maize-ryegrass-soybean [Rg-Mz-Rg-So]; and alfalfa-maize [Alf-Mz]. Soil was sampled from the layers 0-5, 5-10 and 10-20 cm, in cylinders and in blocks with undisturbed structure. In the 0-5 cm layer, bulk density was lowest in the Ot-Mz-Wt-So (0.96 Mg m -3) and Vt-Mz-Wt-So systems (0.93 Mg m -3). In the 5-10 and 10-20 cm layers, the bulk density tended to be lowest in Alf-Mz systems (1.14 and 1.17 Mg m -3, respectively). A similar trend was observed for macroporosity, which in the top layer was greater in Ot-Mz-Wt-So (0.29 m 3 m -3) and Vt-Mz-Wt-So (0.30 m 3 m -3) and in the 5-10 and 10-20 cm layers tended to be greater in the Alf-Mz system (0.19 m 3 m -3). No clear trend was observed for microporosity. The saturated hydraulic conductivity was directly related with macroporosity, and was highest for Vt-Mz-Wt-So in the 0-5 cm layer (224 mm h -1) and Alf-Mz in the layers 5-10 (170 mm h -1) and 10-20 cm (147 mm h -1). In the Vt-Mz-Wt-So system, the mean weight diameter of aggregates was lowest in the 0-5 cm layer (2.39 mm) and highest (3.04 mm) in the Wt-So. The highest cone index values were observed in the Wt-So system, with over 1.5 MPa in the 7.5-22.5 cm layer. The compaction degree was lowest in the Alf-Mz system (0.2 MPa cm). Results were attributed mainly to the role of the crop roots of the systems and to the intensity of machinery traffic. Considering the 0-20 cm layer as a whole, the capacity to promote soil structural quality improvements was greater for the semi-perennial Alf-Mz system than for systems based on annual species. Bi-annual rotation systems, based on cover crops such as black oat and vetch, promote soil structural quality improvements compared to the wheat - soybean succession.