19862015
  • Authors:
    • Honeycutt, C. W.
    • Griffin, T. S.
    • Larkin, R. P.
  • Source: Plant Disease
  • Volume: 94
  • Issue: 12
  • Year: 2010
  • Summary: Seven different 2-year rotations, consisting of barley/clover, canola, green bean, millet/rapeseed, soybean, sweet corn, and potato, all followed by potato, were assessed over 10 years (1997-2006) in a long-term cropping system trial for their effects on the development of soilborne potato diseases, tuber yield, and soil microbial communities. These same rotations were also assessed with and without the addition of a fall cover crop of no-tilled winter rye (except for barley/clover, for which underseeded ryegrass was substituted for clover) over a 4-year period. Canola and rapeseed rotations consistently reduced the severity of Rhizoctonia canker, black scurf, and common scab (18 to 38% reduction), and canola rotations resulted in higher tuber yields than continuous potato or barley/clover (6.8 to 8.2% higher). Addition of the winter rye cover crop further reduced black scurf and common scab (average 12.5 and 7.2% reduction, respectively) across all rotations. The combined effect of a canola or rapeseed rotation and winter rye cover crop reduced disease severity by 35 to 41% for black scurf and 20 to 33% for common scab relative to continuous potato with no cover crop. Verticillium wilt became a prominent disease problem only after four full rotation cycles, with high disease levels in all plots; however, incidence was lowest in barley rotations. Barley/clover and rapeseed rotations resulted in the highest soil bacterial populations and microbial activity, and all rotations had distinct effects on soil microbial community characteristics. Addition of a cover crop also resulted in increases in bacterial populations and microbial activity and had significant effects on soil microbial characteristics, in addition to slightly improving tuber yield (4% increase). Thus, in addition to positive effects in reducing erosion and improving soil quality, effective crop rotations in conjunction with planting cover crops can provide improved control of soilborne diseases. However, this study also demonstrated limitations with 2-year rotations in general, because all rotations resulted in increasing levels of common scab and Verticillium wilt over time.
  • Authors:
    • Petit, S.
    • Waldhardt, R.
    • Munier-Jolain, N.
    • Le Lagadec, L.
    • Meiss, H.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 138
  • Issue: 1-2
  • Year: 2010
  • Summary: Vegetation cover may affect weed seed predation by modifying the habitat quality for predatory organisms. Post-dispersal weed seed predation was measured by placing 'seed cards' in two perennial crops (alfalfa, cocksfoot) with and without crop cutting and in plots with bare soil. Each treatment was repeated four times in a randomized complete block design. Vegetation cover was measured by canopy light interception. Predation trials lasted two weeks and were repeated three times. Seed predation rates varied among three weed species (highest for Viola arvensis, intermediate for Alopecurus myosuroides, lowest for Sinapis arvensis). Vertebrate exclusion cages (12 mm x 12 mm openings) strongly reduced seed predation rates. Positive relationships were observed between vegetation cover and seed predation rates by both vertebrates and invertebrates for all weed species and trials, except when overall predation rates were very low. Predation rates were highest in uncut alfalfa, lowest on bare soil, but 16-64% of this variation could equally be explained by vegetation cover. The factorial design indicated that cutting had a stronger impact than crop species (legume or grass). Results suggest that weed seed predation may be enhanced by maintaining a high and temporally extended vegetation cover. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Lang, J. M.
    • Ebelhar, S. A.
    • Olson, K. R.
  • Source: Soil Science
  • Volume: 175
  • Issue: 2
  • Year: 2010
  • Summary: An 8-year cover crop study was conducted in southern Illinois to evaluate the effects of conservation tillage systems on corn and soybean yields and for the maintenance and restoration of soil organic carbon (SOC) and soil productivity of previously eroded soils. In 2001, the no-till (NT), chisel plow, and moldboard plow (MP) treatment plots, which were replicated six times in a Latin square design, were split (with cover crop and without) on sloping, moderately well-drained, moderately eroded soil. The average corn and average soybean yields were similar for NT, chisel plow, and MP systems with and without cover crops. By 2009, the tillage zone, subsoil, and rooting zone of all treatments had similar SOC on a volume basis for the cover crop treatments as for the same tillage treatment without a cover crop. However, using the baseline 2000 SOC contents only, the NT with cover crops maintained most of the SOC levels in the topsoil and subsoil during the 8-year study, when the sediment was high in SOC and retained in the upland landscape by soil conservation practices, including border and filter strips and sod waterways adjacent to the plots, with and without cover crops. Soil carbon creation retention in the upland landscape was greatest for the MP treatments when sediments were retained by the soil conservation practices, which should reduce soil erosion and sediment rich in SOC being transported by overland flow into water and the eventual release of methane and carbon dioxide to the atmosphere.
  • Authors:
    • Brandenburg, R. L.
    • Pembroke, B.
    • Gowen, S. R.
    • Osei, K.
    • Jordan, D. L.
  • Source: Journal of Nematology
  • Volume: 42
  • Issue: 3
  • Year: 2010
  • Summary: Root-knot nematode is an important pest in agricultural production worldwide. Crop rotation is the only management strategy in some production systems, especially for resource poor farmers in developing countries. A series of experiments was conducted in the laboratory with several leguminous cover crops to investigate their potential for managing a mixture of root-knot nematodes (Meloidogyne arenaria M. incognita, M. javanica). The root-knot nematode mixture failed to multiply on Mucuna pruriens and Crotalaria spectabilis but on Dolichos lablab the population increased more than 2-fold when inoculated with 500 and 1,000 nematodes per plant. There was no root-galling on M. pruriens and C. spectabilis but the gall rating was noted on D. lablab. Greater mortality of juvenile root-knot nematodes occurred when exposed to eluants of roots and leaves of leguminous crops than those of tomato; 48.7% of juveniles died after 72 It exposure to root eluant of C. spectabilis. The leaf eluant of D. lablab was toxic to nematodes but the root eluant was not. Thus, different parts of a botanical contain different active ingredients or different concentrations of the same active ingredient. The numbers of root-knot nematode eggs that hatched in root exudates of M. pruriens and C. spectabilis were significantly lower (20% and 26%) than in distilled water, tomato and P vulgaris root exudates (83%, 72% and 89%) respectively. Tomato lacks nematotoxic compounds found in M. pruriens and C. spectabilis. Three months after inoculating plants with 1,000 root-knot nematode juveniles the populations in pots with M. prurient, C. spectabilis and C. retusa had been reduced by approximately 79%, 85% and 86% respectively; compared with an increase of 262% nematodes in pots with Phaseolus vulgaris. There was significant reduction of 90% nematodes in fallow pots with no growing plant. The results from this study demonstrate that some leguminous species contain compounds that either kill root-knot nematodes or interfere with hatching and affect their capacity to invade and develop within their roots. M. pruriens, C. spectabilis and C. retusa could be used with effect to decrease a mixed field populations of root-knot nematodes.
  • Authors:
    • Saulas, P.
    • Ghiloufi, M.
    • Picard, D.
    • de Tourdonnet, S.
  • Source: Field Crops Research
  • Volume: 115
  • Issue: 1
  • Year: 2010
  • Summary: The sustainability of cropping systems can be increased by introducing a cover crop, provided that the cover crop does not reduce the cash crop yield through competition. The cover crop may be sown at the same time as a cash crop in the crop rotation. We carried out an experiment in 1999-2000 and 2000-2001 in the Paris Basin, to analyze the effects of simultaneously sowing winter wheat (Triticum aestivum L.) and red fescue (Festuca rubra L.), a turf grass. Competition between wheat and fescue was analyzed with one variety of red fescue, Sunset, and two varieties of wheat, Isengrain and Scipion, each sown at a density of 150 plants m(-2). In this study, we evaluated the effect of undersown fescue on wheat yield and analyzed the competition between the two species in detail. The undersown red fescue decreased wheat yield by about 12% for Isengrain (8.7 t ha(-1) for undersown Isengrain versus 9.8 t ha(-1) for Isengrain alone) and 7% for Scipion (7.4 t ha(-1) for undersown Scipion versus 8.0 t ha(-1) for Scipion alone). During the early stages of wheat growth (up to the '1 cm ear' stage, corresponding to stage 30 on Zadoks' scale), undersown fescue and fescue sown alone grew similarly. However, fescue biomass levels were much lower (5.6 and 4.7 g m(-2) for fescue grown alone and undersown fescue) than wheat biomass levels on the undersown plots (1120 g m(-2) for Isengrain and 111 g m(-2) for Scipion). From the e1 stage onwards, the wheat canopy rapidly extended, whereas that of red fescue remained sparse. The time lag between the beginning of the rapid increase in LAI and PAR interception by wheat grown alone and that for fescue grown alone was 590 dd in the second year. This resulted in much slower growth rates for undersown fescue than for undersown wheat. Biomass production rate was therefore low for undersown fescue (12% those of fescue grown alone, on average, at the time of wheat harvest), as were levels of water and nitrogen use. Neither the water deficit that occurred during the second experiment nor the nitrogen nutrition status of the wheat on plots with undersown fescue significantly affected wheat biomass production after anthesis. The global interception efficiency index IG epsilon(i) indicated that the fraction of the PAR(o) intercepted by the wheat during its growth (255 days) was 0.35. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Arriaga, F. J.
    • Rogers, H. H.
    • Runion, G. B.
    • Prior, S. A.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 2
  • Year: 2010
  • Summary: Increasing atmospheric CO(2) concentration has led to concerns about potential effects on production agriculture. In the fall of 1997, a study was initiated to compare the response of two crop management systems (conventional tillage and no-tillage) to elevated CO(2). The study used a split-plot design replicated three times with two management systems as main plots and two atmospheric CO(2) levels (ambient and twice ambient) as split plots using open-top chambers on a Decatur silt learn soil (clayey, kaolinitic, thermic Rhodic Paleudults). The conventional system was a grain sorghum [Sorghum bicolor (L.) Moench.] and soybean (Glycine max (L.) Merr.] rotation with winter fallow and spring tillage practices. In the no-tillage system, sorghum and soybean were rotated, and three cover crops were used [crimson clover (Trifolium incarnatum L.), sunn hemp (Crotalaria juncea L.), and wheat (Triticum aestivum L.)]. Over multiple growing seasons, the effect of management and CO(2) concentration on leaf-level gas exchange during row crop (soybean in 1999, 2001, and 2003; sorghum in 2000, 2002, and 2004) reproductive growth were evaluated. Treatment effects were fairly consistent across years. In general, higher photosynthetic races were observed under CO(2) enrichment (more so with soybean) regardless of residue management practice. Elevated CO(2) led to decreases in stomatal conductance and transpiration, which resulted in increased water use efficiency. The effects of management system on gas exchange measurements were infrequently significant, as were interactions of CO(2) and management. These results Suggest that better soil moisture conservation and high rates of photosynthesis can occur in both tillage systems in CO(2)-enriched environments during reproductive growth.
  • Authors:
    • Helmers, M. J.
    • Qi, Z.
  • Source: Vadose Zone Journal
  • Volume: 9
  • Issue: 1
  • Year: 2010
  • Summary: Utilization of cereal rye (Secale cereale L. ssp. cereal) as a winter cover crop has potential benefits for subsurface drainage and NO(3) loss reduction. The objective of this study was to quantify the soil water balance components and impacts of a rye cover crop on subsurface drainage in central Iowa. Rye was planted in lysimeters in mid-October and terminated in early June in 3 yr and the lysimeters were left fallow during the summer months. Subsurface drainage water was generally pumped out weekly along with taking soil moisture measurements; however, multiple appreciable rain events in a given week required more frequent pumping. During May through July of the 3 yr, monthly subsurface drainage was significantly reduced by 21% when comparing the rye system to bare soil (P
  • Authors:
    • Launay, M.
    • Tourdonnet, S. de
    • Shili-Touzi, I.
    • Dore, T.
  • Source: Field Crops Research
  • Volume: 116
  • Issue: 3
  • Year: 2010
  • Summary: The introduction of a living cover crop during a cash crop growth cycle (relay intercropping) and its maintenance after the cash crop harvest may help to preserve biodiversity, increase soil organic matter content and carbon sequestration and provide other ecosystem services, such as natural pest regulation or nutrient recycling, by increasing useful biotic interactions within the agroecosystem. We studied the impact of various approaches to manage a red fescue cover crop in a winter wheat crop in terms of light, water and nitrogen competition, using the STICS crop model adapted for intercropping. The STICS model for wheat/fescue intercropping was first evaluated on two years of experimental data obtained in the field. It gave satisfactory statistical results for the prediction of dry matter, leaf area index (LAI) and nitrogen accumulation in the two species, and for nitrogen and water dynamics in the soil. By simulating unmeasured variables, such as transpiration, the model improves our understanding of the performance of the intercrop in the field. For example, we showed that the intercropping system was more efficient that wheat grown as a sole crop, in terms of nitrogen accumulation and decreasing soil nitrogen levels before the leaching period. However, it also resulted in lower wheat yields. We then used the STICS model to compare four intercropping management scenarios differing in terms of the date of red fescue emergence, over 35 climatic years. We found that, in most climatic scenarios, the emergence of the fescue crop during the late tillering phase of the wheat crop gave the best compromise between wheat yield overall nitrogen accumulation and radiation interception.
  • Authors:
    • Ferrero, A.
    • Tesio, F.
  • Source: International Journal of Sustainable Development & World Ecology
  • Volume: 17
  • Issue: 5
  • Year: 2010
  • Summary: The exploitation of crop allelopathy against weeds may be useful to reduce issues related to the use of herbicides. Several crops, such as alfalfa, barley, black mustard, buckwheat, rice, sorghum, sunflower and wheat, demonstrate strong weed suppression ability, either by exuding allelochemical compounds from living plant parts or from decomposing residues. As well as the positive effect on weed reduction, the introduction in agronomic rotations of allelopathic crops, their use as a mulch to smother crops or as a green manure may also be helpful in reduction of other agricultural problems, such as environmental pollution, use of unsafe products and human health concerns, through a reduction in chemical inputs. Knowledge of allelopathic properties of crops may also be advantageous in mitigation of soil sickness. Moreover, information on weed allelopathy may be profitable in preventing serious crop damage if the weed biomass is buried in the soil, and a crop susceptible to allellochemicals is planned for the following year. The use of allelopathic traits from crops or cultivars with important weed inhibition qualities, together with common weed control strategies, can play an important role in the establishment of sustainable agriculture.
  • Authors:
    • Thierfelder, C.
    • Wall, P. C.
  • Source: Experimental Agriculture
  • Volume: 46
  • Issue: 3
  • Year: 2010
  • Summary: Conservation agriculture (CA) systems are based on minimal soil disturbance, crop residue retention and crop rotation. Although the capacity of rotations to break pest and disease cycles is generally recognized, other benefits of crop rotations in CA systems are seldom acknowledged and little understood. We monitored different conventional and CA cropping systems over the period from 2005 to 2009 in a multi-seasonal trial in Monze, southern Zambia. Both monocropped maize and different maize rotations including cotton and the green manure cover crop sunnhemp (Crotalaria juncea) were compared under CA conditions, with the aim of elucidating the effects of crop rotations on soil quality soil moisture relations and maize productivity. Infiltration, a sensitive indicator of soil quality, was significantly lower on conventionally ploughed plots in all cropping seasons compared to CA plots. Higher water infiltration rate led to greater soil moisture content in CA maize treatments seeded alter cotton. Earthworm populations, total carbon and aggregate stability were also significantly higher on CA plots. improvements in soil quality resulted in higher rainfall use efficiency and higher maize grain yield on CA plots especially those in a two- or three-year rotation. lit the 2007/08 and 2008/2009 season, highest yields were obtained from direct-seeded maize after sunnhemp, which yielded 74% and 136% more than maize in the conventionally ploughed control treatment with a continuous maize crop. Even in a two-year rotation (maize-cotton), without a legume green manure cover crop, 47% and 38% higher maize yields were recorded compared to maize in the conventionally ploughed control in the two years, respectively This suggests that there are positive effects from crop rotations even in the absence of disease and pest problems. The overall profitability of each system will, however, depend on markets and prices, which will guide the farmer's decision on which, Wally, rotation to choose,