• Authors:
    • Barbercheck, M. E.
    • Jabbour, R.
  • Source: Biological Control
  • Volume: 51
  • Issue: 3
  • Year: 2009
  • Summary: The growing demand for organic products creates opportunities for farmers. Information on the consequences of management practices can help farmers transition to organic and take advantage of these prospects. We examined the interaction between soil disturbance and initial cover crop on naturally occurring entomopathogenic fungi (EPF) during the 3-year transition to organic production in a feed grain rotation in central Pennsylvania. Our experiment included four systems comprised of a factorial combination of two levels of primary tillage (full vs. reduced) and two types of initial cover crop (timothy/clover vs. rye/vetch). The cropping sequence consisted of an initial cover crop, followed by soybean, and finally, maize. The entire experiment was replicated in time, with the initiation lagged by 1 year. We detected four species of EPF (Metarhizium anisopliae, Beauveria bassiana, Isaria fumosorosea, and Isaria farinosa) by bioassay of soil samples collected four times during each field season. The latter three species were detected infrequently; therefore, we focused statistical analysis on M. anisopliae. Detection of M. anisopliae varied across sampling date, year in crop sequence, and experimental start, with no consistent trend across the 3-year transition period. M. anisopliae was isolated more frequently in the systems initiated with timothy/clover cover crops and utilizing full tillage; however, we only observed a tillage effect in one temporal replicate. M. anisopliae detection was negatively associated with soil moisture, organic matter, and zinc, sulfur, and copper concentrations in the soil. This study helps to inform farmers about management effects on soil function, specifically conservation biological control. (C) 2009 Elsevier Inc. All rights reserved.
  • Authors:
    • Bergtold, J. S.
    • Raper, R. L.
    • Price, A. J.
    • Kornecki, T. S.
  • Source: Applied Engineering in Agriculture
  • Volume: 25
  • Issue: 6
  • Year: 2009
  • Summary: In a weed-free field with ideal weather conditions, a cash crop can be planted 3 weeks after rolling a mature cereal rye winter cover crop without using herbicides. However, cloudy and wet weather can delay the rolling and/or desiccation of rye, thereby delaying cash crop planting which can negatively impact yield. One effective way to reduce the time between rolling and planting is to spray herbicide while rolling. However, a continuous spray may not be required if a roller/crimper is used due to the additive effect of the roller. Two different methods of applying glyphosate (Roundup (TM)) to rolled rye were compared. First, a felt strip saturated with herbicide was attached to the roller's crimping bar to provide glyphosate application with every crimp. The second method consisted of a boom (five nozzles controlled by solenoid valves) mounted on the roller applying a spray continuously, and intermittent spray every second crimp, or every fourth crimp. The average results over three growing seasons showed that 7 days after rolling, rye termination rates for all rolled/glyphosate treatments surpassed 90% (91% for glyphosate saturated felt strip and 98% for continuous spray), exceeding the termination rates for rye recommended to planting cash crops into rye residue cover. For the roller/crimper alone and the non-treated check (standing rye), termination rates were 82% and 54%, respectively. Since spraying glyphosate every fourth crimp provided a 93% termination rate one week after rolling, this method may facilitate planting the cash crop in a timely fashion while reducing input costs. Economic savings of $12.63 to $36.87 ha(1) may be attained by incorporating herbicide applications with rolling activities. One and two weeks after the rolling treatment, volumetric soil moisture content for all rolled rye/chemical treatments were significantly higher than the non-treated check.
  • Authors:
    • Bielders, C. L.
    • Laloy, E.
  • Source: European Journal of Soil Science
  • Volume: 60
  • Issue: 6
  • Year: 2009
  • Summary: In order to evaluate the impact of intercrop management on runoff and erosion in a continuous maize cropping system, the plot scale, continuous and process-based erosion model (CREHDYS) developed previously must be calibrated accounting for its two main outputs: runoff and sediment loss. To do that, a global Pareto multi-objective calibration was applied to these two potentially conflicting objectives, considering daily runoff and periodical erosion rates, for two sites with different slopes and soil textures. This revealed a trade-off between both objectives. The large resulting Pareto uncertainty regarding parameters did not translate into a large predictive uncertainty of daily runoff but resulted into a large uncertainty on erosion prediction. Globally, model results were satisfactory with regard to daily runoff prediction (Nash-Sutcliffe index varying within the Pareto solution set from 0.65 to 0.91 for calibration and 0.64 to 0.77 for validation period) and relatively satisfactory for periodical erosion. However, the small number of available data points (three) for model validation in terms of periodical erosion prediction was not sufficient to ensure a proper validation. The calibrated model was in turn used to perform a scenario analysis of the long-term hydrological and erosive impact of inter-cropping period management in a continuous maize cropping system, using disaggregated rainfall. The long-term simulations mainly revealed that, with regard to the erosion prevention during the inter-cropping period, planting a winter cover crop is a better option than reduced tillage with a cultivator (0-12 cm), even if the cover is destroyed early (1 January). As compared with the situation of a bare heavily crusted soil with two semi-permanent wheel tracks, reduced tillage led to an erosion reduction from 90 to 97%, an early cover destruction (1 January) to an erosion decrease from 92 to 98% and a cover destroyed on 1 March or later to an average soil loss reduction from 96 to 99%.
  • Authors:
    • Fernandes, C.
    • Cora, J. E.
    • Marcelo, A. V.
    • Martins, M. dos R.
    • Jorge, R. F.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 33
  • Issue: 2
  • Year: 2009
  • Summary: Decomposing crop residues in no-tillage system can alter soil chemical properties, which may consequently influence the productivity of succession crops. The objective of this study was to evaluate soil chemical properties and soyabean, maize and rice yield, grown in the summer, after winter crops in a no-tillage system. The experiment was carried out in Jaboticabal, Sao Paulo, Brazil on a Red Latosol (Oxisol), in a completely randomized block design, in strip plots with three replications. The treatments consisted of four summer crop sequences (maize monocrop, soyabean monocrop, soyabean/maize rotation and rice/bean/cotton rotation) combined with seven winter crops (maize, sunflower, oilseed radish, pearl millet, pigeon pea, grain sorghum and sunn hemp). The experiment began in September 2002. After the winter crops in the 2005/2006 growing season and before the sowing of summer crops in the 2006/2007 season, soil samples were collected in the layers 0-2.5; 2.5-5.0; 5-10; 10-20; and 20-30 cm. Organic matter, pH, P, K +, Ca 2+, Mg 2+, and H+Al were determined in each soil sample. In the summer soyabean/maize rotation and in maize the organic matter contents and P levels were lower, in the layers 0-10 cm and 0-20 cm, respectively. Summer rice/bean/cotton rotation increased soil K levels at 0-10 cm depth when sunn hemp and oilseed radish had previously been grown in the winter, and in the 0-2.5 cm layer for millet. Sunn hemp, millet, oilseed radish and sorghum grown in the winter increased organic matter contents in the soil down to 30 cm. Higher P levels were found at the depths 0-2.5 cm and 0-5 cm, respectively, when sunn hemp and oilseed radish were grown in the winter. Highest grain yields for soyabean in monoculture were obtained in succession to winter oilseed radish and sunn hemp and in rotation with maize, after oilseed radish, sunn hemp and millet. Maize yields were highest in succession to winter oilseed radish, millet and pigeon pea. Rice yields were lowest when grown after sorghum.
  • Authors:
    • Jorge, R. F.
    • Cora, J. E.
    • Martins, M. dos R.
    • Marcelo, A. V.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 1
  • Year: 2009
  • Summary: The adaptation of no-tillage system in tropical regions depends on the suitable choice of summer and winter crops which should contribute to improvement of soil properties. The aim of the present study was to determine the effect of crop sequences on soil aggregation and contents of organic C and polysaccharides in aggregates of a Rhodic Eutrudox under no-tillage. The treatments consisted of the combination of four summer crop sequences and seven winter crop sequences. The summer crop sequences were: maize monocrop ( Zea mays L.) (MM); soybean monocrop ( Glycine max (L.) Merrill) (SS); crop sequence of soybean/maize/soybean/maize (SM); crop sequence of rice ( Oryza sativa L.)/bean ( Phaseolus vulgaris L.)/cotton ( Gossypium hirsutum L.)/bean (RB). The winter crops were: maize, sunflower ( Helianthus annuus L.), radish ( Raphanus sativus L.), pearl millet ( Pennisetum americanum (L.) Leeke), pigeon pea ( Cajanus cajan (L.) Millsp), grain sorghum ( Sorghum bicolor (L.) Moench) and sunn hemp ( Crotalaria juncea L.). The highest total organic C, total polysaccharides and dilute acid-extracted polysaccharides contents were found in 2.00-1.00 mm water-stable aggregates and the lowest contents were found in
  • Authors:
    • Doré, T.
    • Lucas, P.
    • Faloya, V.
    • Montfort, F.
    • Motisi, N.
  • Source: Field Crops Research
  • Volume: 113
  • Issue: 3
  • Year: 2009
  • Summary: Biofumigation is increasingly viewed as a potentially useful technique for controlling soil-borne crop pathogens, but its efficacy has not systematically been demonstrated at field scale. We investigated the differences in efficacy observed in the field, by analysing the mechanisms by which a Brassica cover crop can act as a biofumigant crop in the prevention of soil-borne disease development. We hypothesised that the biofumigant crop might have a negative effect on soil-borne pathogens whilst growing, and that the pulverisation of this crop and the incorporation of its residues into the soil may enhance this effect. We tested this hypothesis by carrying out three field experiments in 2006, 2007 and 2008 in which Brassica juncea (brown mustard) was managed in different ways within a sugar beet-winter wheat rotation and analysing effects on sugar beet root rot caused by Rhizoctonia solani. Three treatments were studied: mustard pulled out at flowering (MP), mustard crushed at flowering and incorporated into the soil (MC) and bare soil (BS) as a control. We assessed the effect of each treatment on root rot incidence and severity at harvest. Over the 3 years of the experiment, disease incidence was significantly higher on BS plots than on the other plots and was significantly higher on MP plots than on MC plots. MC treatment gave a significantly lower mean conditional severity (severity calculated for diseased beets only) than the BS and MP treatments. Mustard residue incorporation was consistently effective at decreasing disease incidence from year to year (43, 44 and 47% efficacy, as determined by comparison with the disease incidence on BS plots, in 2006, 2007 and 2008, respectively), but the efficacy of growing mustard was variable (36, 16 and 39% efficacy in 2006, 2007 and 2008, respectively). These findings provide insight into the mechanisms by which biofumigant crops may affect soil-borne diseases. These findings have implications for the possible use of biofumigant crops as a biological method for controlling soil-borne diseases at the field scale. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Deen, W.
    • Earl, H.
    • Queen, A.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 6
  • Year: 2009
  • Summary: Red clover (Trifolium pratense L.) use as an underseeded cover crop in winter cereals has declined due to inability of growers to consistently establish uniform stands. The objective of this study was to assess the effect of light and soil moisture competition on underseeded red clover establishment and end of season dry matter production. Field trials were conducted at multiple locations in 2005 and 2006 in Ontario, Canada. Wheat (Triticum aestivum L.) N rate (67 and 135 kg N ha(-1)) and row thinning treatments (19-cm rows, every third 19-cm row removed at the 4-5 leaf stage) were used to alter light penetration and soil moisture competition. The high N rate and row thinning treatments consistently reduced light penetration, beginning as early as wheat stem elongation initiation, but had no effect on soil gravimetric moisture content. Soil moisture was primarily affected by location and year. Red clover dry weight in 2005, a relatively dry year, ranged from 688 to 1184 kg ha(-1), and in 2006, a relatively wet year, ranged from 2336 to 2805 kg ha(-1). Average final red clover stand count was 23 plants m(-2) in 2005 and 55 plants m(-2) in 2006. In 2005, plant mortality occurred before wheat anthesis. In both years, and at most locations, red clover final dry weight was positively correlated with light penetration, again beginning as early as initiation of wheat stem elongation. Final red clover dry weight in both years and red clover stand count in 2005 were correlated with soil gravimetric water content during wheat anthesis, but this was primarily due to location and year effects. Although both light penetration through the wheat canopy and soil moisture influence biomass production of underseeded red Clover, soil moisture has the greater influence and is altered very little by wheat management.
  • Authors:
    • Raper, R. L.
    • Reddy, K. C.
    • Nyakatawa, E. Z.
    • Reddy, S. S.
    • Reeves, D. W.
    • Lemunyon, J. L.
  • Source: Field Crops Research
  • Volume: 114
  • Issue: 2
  • Year: 2009
  • Summary: Long-term field experiments are needed to fully realize positive and negative impacts of conservation tillage and poultry litter application. A study was initiated on a Decatur silt loam soil at the Tennessee Valley Research and Extension Center, Belle Mina, AL, USA in 1996 to evaluate cotton (Gossypium hirsutum L.) performance with long-term poultry litter (PL) application under different tillages and to Study the build up of phosphorus (P) With application of PL. Treatments include incomplete factorial combinations of three tillage systems [conventional till (CT), mulch till (MT), and no-till (NT)], two cropping systems [cotton-fallow and cotton-winter rye (Secale cereale L.)], and two nitrogen sources and rates [100 kg N ha(-1) from ammonium nitrate (AN), and 100 and 200 kg N ha(-1) from poultry litter (PL)]. Cotton was rotated with corn (Zea mays L.) every third year. Results from 2003 to 2008 showed that all tillages gave similar cotton lint yields with AN at 100 kg N ha(-1). Application of PL at 100 kg N ha(-1) in NT plots resulted in 12 and 11% yield reductions compared to that of CT and MT, respectively. However, NT plots with higher quantity of PL (200 kg N ha(-1)) gave similar yields to CT and MT at 100 kg N ha(-1). During corn years, higher residual fertility of PL, in terms of grain yields, was observed in NT plots compared to CT and MT. Long-term PL application (100 kg N ha(-1) year(-1)) helped to maintain original soil pH in CT and MT while AN application decreased soil pH. In NT plots, PL at 100 kg N ha(-1) was not sufficient to maintain original soil pH, but 200 kg N ha(-1) maintained original pH. Although not-significant, elevated P levels were observed in all tillages compared to original P levels which indicates possibility of P build up in future with further application of PL. Application of PL at double rate (200 kg N ha(-1)) in NT plots resulted in significant build up of P. Results indicate that NT gives similar yields to CT when received AN. but needs higher rate of PL application to achieve similar yields to CT. (C) 2009 Elsevier B,V. All rights reserved.
  • Authors:
    • Wall, P. C.
    • Thierfelder, C.
  • Source: Soil & Tillage Research
  • Volume: 105
  • Issue: 2
  • Year: 2009
  • Summary: The adoption of conservation agriculture (CA), based on minimal soil movement, permanent soil cover with crop residues or growing plants and crop rotation has advanced rapidly in the Americas and Australia over the last three decades. One of the immediate benefits of CA in dryland agriculture is improved rainfall-use efficiency through increased water infiltration and decreased evaporation from the soil surface, with associated decreases in runoff and soil erosion. This paper focuses on the effect of CA techniques on soil moisture relations in two researcher-managed trials in Zambia and Zimbabwe. In 2005/2006 and 2006/2007, we found significantly higher water infiltration on both sites on CA fields compared to conventionally ploughed fields. At Henderson Research Station, Zimbabwe, on a sandy soil, a direct seeded CA treatments had a 49% and 45% greater infiltration rate than the conventionally tilled plots after a simulated rainfall in both seasons. At Monze Farmer Training Centre, Zambia, on a finer-textured soil, the same treatment had 57% and 87% greater infiltration rate than the conventionally tilled control treatment in both seasons. Treatments that included reduced tillage and surface residue retention had less water runoff and erosion on runoff plots at Henderson Research Station, Zimbabwe. On average, soil moisture was higher throughout the season in most CA treatments than in the conventionally tilled plots. However, the full potential of CA in mitigating drought was not evident as there was no significant drought period in either season. Results suggest that CA has the potential to increase the productivity of rainfall water and therefore reduce the risk of crop failure, as was apparent at the Monze Farmer Training Centre, Zambia, in 2005/2006 when a period of moisture stress at tassling affected CA treatments less than the conventionally tilled treatment. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Gao, L.
    • Chen, Q.
    • Liu, J.
    • Zhang, X.
    • Tian, Y.
  • Source: Scientia Horticulturae
  • Volume: 123
  • Issue: 2
  • Year: 2009
  • Summary: The increased use of rotation, grafting, and soil sterilization has been documented to increase crop yield in intensive vegetable production systems in China. It is believed that these practices can promote changes in the rhizosphere that enhance early growth of plants. A 2-year greenhouse experiment on tomato double-cropping systems was conducted to investigate the effects of different agricultural treatments on microbial properties of rhizosphere soils and tomato fruit yield. The treatments included planting of welsh onion as a cover crop in the summer fallow (SF) period (CW), rotating vegetable chrysanthemum and tomato (CT), planting graft-tomato instead of auto-root tomato (GT), sterilizing soil with calcium cyanamide in the SF period (TC), and fallowing in the SF period (Control). Microbial population was analyzed by dilution plating. In general, microbial populations were higher in CT, CT and TC than in control. Fungal population was higher in TC whereas a high number of bacteria were found in CT. Soil microbial biomass C and N, total microbial population, organic C and total N showed significant positive correlations (P