• Authors:
    • Bidders, C. L.
    • Laloy, E.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 3
  • Year: 2010
  • Summary: The management of winter cover crops is likely to influence their performance in reducing runoff and erosion during the intercropping period that precedes spring crops but also during the subsequent spring crop This study investigated the impact of two dates of destruction and burial of a rye (Secale cereale L.) and ryegrass (Lolium multifloruni Lint) cover crop on runoff and erosion, focusing on a continuous silage maize (Zea mays L) cropping system Thirty erosion plots with various intercrop management options were monitored for 3 yr at two sues. During the intercropping period. cover crops reduced runoff and erosion by more than 94% compared with muffled, post-maize harvest plots Rough tillage after maize harvest proved equally effective as a late sown cover crop There was no effect of cover crop destruction and burial dates on runoff and erosion during the intercropping period. probably because rough tillage for cover crop burial compensates for the lack of soil cover During two of the monitored maize seasons. it was observed that plots that had been covered during the previous intercropping period lost 40 to 90% less soil compared with maize plots that had been left bare during the intercropping period The burial of an aboveground cover crop biomass in excess of 1 5 t ha (1) was a necessary, yet not always sufficient. condition to induce a residual effect. Because of the possible beneficial residual effect of cover crop burial on erosion reduction, the sowing of a cover crop should be preferred over rough tillage after maize harvest
  • 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:
    • Kismanyoky, A.
    • Lehoczky, E.
  • Source: Novenytermeles OR ACTA PHYTOPATHOLOGICA ET ENTOMOLOGICA HUNGARICA or Agrokémia és Talajtan ?
  • Volume: 59
  • Issue: Supplement
  • Year: 2010
  • Summary: Soil cultivation (the factor A) and nitrogen fertilization (the factor B) effects on yields of winter wheat and maize and weeds-cover was tested in the long-term experiment conducted on Keszthely Eutric cambisol (Ramann type brown forest soil) in 2005-2008 period. The bi-factorial trial was arranged in split plot design with four replications (basic plots 435 m 2 and 87 m 2, for A and B, respectively). Conventional tillage (ploughing=PL), no-till drill (NT) and disking (D) were the treatment of soil cultivation, while five rates of nitrogen (kg N ha -1: 0; 120; 180; 240; 300) were applied on blanket application of phosphorus and potassium (kg ha -1: 100 P 2O 5+100 K 2O). There was no weed control until our investigation. The weed surveys were made with Balazs-Ujvarosi coenological method. The fewer yields were obtained in the wheat-maize no-tillage system compared to the others. It was proved at high and low level alike (good and unfavourable years). In the average of years the decreasing of yield was 10-15% compared to the traditional cultivation. In survey the weed cover (%) at wheat in springtime it can be said that the weed cover increased parallel with the amount of N fertilizer and above 200 kg/ha N doses declined. The dynamic of relation of weeds v.s. N fertilizer it is similar to the square equation of yield curve. In case of maize there were not significant differences between the N treatments (25-30%) regarding the weed cover. The results draw ones attention to that facts that with the propagation of the reduced soil cultivation systems it is necessary to modify and harmonize the practice of weed control and fertilization.
  • Authors:
    • Lehoczky, É.
    • Kismányoky, A.
  • Source: Agrokémia és Talajtan
  • Volume: 59
  • Issue: 1
  • Year: 2010
  • Summary: A long-term soil tillage experiment was conducted in 2005 to 2008 on a Ramann-type brown forest soil (Eutric Cambisol) in Keszthely, Hungary, with different cultivation methods (no-till, drill, disc tillage, conventional tillage (ploughing)) and five increasing N doses. Treatment A was the cultivation method: conventional tillage (ploughing), no-till, drill, disc tillage; and Treatment B was N fertilizer application: N 0-N 4 (0, 120, 180, 240 and 300 for maize, and 0, 120, 160, 200 and 240 kg/ha per ton for wheat, respectively). Both plots received a blanket application of 100 kg P 2O 5/ha and 100 kg K 2O/ha. With soil cultivation and N fertilization treatments, winter wheat yield varied between 2.5 and 6.0, while maize yield ranged from 6 to 10 t/ha. The influence of the annual circumstances (mostly rainfall) on the yields was measurable and from time to time statistically significant. The different amounts of N fertilizer significantly increased the yields of maize and wheat. The highest increases were found in the case of N 1 and N 2 treatments. The maximum yields of maize and wheat were obtained with the 200-250 kg N/ha doses. On the average of years, the largest weed cover (28%) was recorded in the no-tillage treatment, while the ploughing system was the least weedy (10-15%).
  • Authors:
    • Yang, D. W.
    • Lei, H. M.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 11
  • Year: 2010
  • Summary: In China, croplands account for a relatively large form of vegetation cover. Quantifying carbon dioxide exchange and understanding the environmental controls on carbon fluxes over croplands are critical in understanding regional carbon budgets and ecosystem behaviors. In this study, the net ecosystem exchange (NEE) at a winter wheat/summer maize rotation cropping site, representative of the main cropping system in the North China Plain, was continuously measured using the eddy covariance technique from 2005 to 2009. In order to interpret the abiotic factors regulating NEE, NEE was partitioned into gross primary production (GPP) and ecosystem respiration (R(eco)). Daytime R(eco) was extrapolated from the relationship between nighttime NEE and soil temperature under high turbulent conditions. GPP was then estimated by subtracting daytime NEE from the daytime estimates of R(eco). Results show that the seasonal patterns of the temperature responses of R(eco) and light-response parameters are closely related to the crop phenology. Daily R(eco) was highly dependent on both daily GPP and air temperature. Interannual variability showed that GPP and R(eco) were mainly controlled by temperature. Water availability also exerted a limit on R(eco). The annual NEE was -585 and -533 g C m-2 for two seasons of 2006-2007 and 2007-2008, respectively, and the wheat field absorbed more carbon than the maize field. Thus, we concluded that this cropland was a strong carbon sink. However, when the grain harvest was taken into account, the wheat field was diminished into a weak carbon sink, whereas the maize field was converted into a weak carbon source. The observations showed that severe drought occurring during winter did not reduce wheat yield (or integrated NEE) when sufficient irrigation was carried out during spring.
  • Authors:
    • Ediriwickrema, J.
    • Shao, Y.
    • Lunetta, R. S.
    • Lyon, J. G.
  • Source: International Journal of Applied Earth Observation and Geoinformation
  • Volume: 12
  • Issue: 2
  • Year: 2010
  • Summary: The Moderate Resolution Imaging Spectrometer (MODIS) Normalized Difference Vegetation Index (NDVI) 16-day composite data product (MOD12Q) was used to develop annual cropland and crop-specific map products (corn, soybeans, and wheat) for the Laurentian Great Lakes Basin (GLB). The crop area distributions and changes in crop rotations were characterized by comparing annual crop map products for 2005, 2006, and 2007. The total acreages for corn and soybeans were relatively balanced for calendar years 2005 (31,462 km(2) and 31,283 km(2), respectively) and 2006 (30,766 km(2) and 30,972 km(2), respectively). Conversely, corn acreage increased approximately 21% from 2006 to 2007, while soybean and wheat acreage decreased approximately 9% and 21%, respectively. Two-year crop rotational change analyses were conducted for the 2005-2006 and 2006-2007 time periods. The large increase in corn acreages for 2007 introduced crop rotation changes across the GLB. Compared to 2005-2006, crop rotation patterns for 2006-2007 resulted in increased corn-corn, soybean-corn, and wheat-corn rotations. The increased corn acreages could have potential negative impacts on nutrient loadings, pesticide exposures, and sediment-mediated habitat degradation. Increased in US corn acreages in 2007 were related to new biofuel mandates, while Canadian increases were attributed to higher world-wide corn prices. Additional study is needed to determine the potential impacts of increases in corn-based ethanol agricultural production on watershed ecosystems and receiving waters. Published by Elsevier B.V.
  • Authors:
    • Delve, R. J.
    • Zingore, S.
    • Nyawasha, R. W.
    • Nyamangara, J.
    • Masvaya, E. N.
    • Giller, K. E.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 88
  • Issue: 1
  • Year: 2010
  • Summary: This paper examines a number of agronomic field experiments in different regions of sub-Saharan Africa to assess the associated variability in the efficiencies with which applied and available nutrients are taken up by crops under a wide range of management and environmental conditions. We consider N and P capture efficiencies (NCE and PCE, kg uptake kg(-1) nutrient availability), and N and P recovery efficiencies (NRE and PRE, kg uptake kg(-1) nutrient added). The analyzed cropping systems employed different soil fertility management practices that included (1) N and P mineral fertilizers (as sole or their combinations) (2) cattle manure composted then applied or applied directly to fields through animal corralling, and legume based systems separated into (3) improved fallows/cover crops-cereal sequences, and (4) grain legume-cereal rotations. Crop responses to added nutrients varied widely, which is a logical consequence of the wide diversity in the balance of production resources across regions from arid through wet tropics, coupled with an equally large array of management practices and inter-season variability. The NCE ranged from 0.05 to 0.98 kg kg(-1) for the different systems (NP fertilizers, 0.16-0.98; fallow/cover crops, 0.05-0.75; animal manure, 0.10-0.74 kg kg(-1)), while PCE ranged from 0.09 to 0.71 kg kg(-1), depending on soil conditions. The respective NREs averaged 0.38, 0.23 and 0.25 kg kg(-1). Cases were found where NREs were > 1 for mineral fertilizers or negative when poor quality manure immobilized soil N, while response to P was in many cases poor due to P fixation by soils. Other than good agronomy, it was apparent that flexible systems of fertilization that vary N input according to the current seasonal rainfall pattern offer opportunities for high resource capture and recovery efficiencies in semi-arid areas. We suggest the use of cropping systems modeling approaches to hasten the understanding of Africa's complex cropping systems.
  • 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:
    • Dagar, J. C.
    • Chaudhari, S. K.
    • Pandey, C. B.
    • Singh, G. B.
    • Singh, R. K.
  • Source: Soil & Tillage Research
  • Volume: 110
  • Issue: 1
  • Year: 2010
  • Summary: Tillage is known to reduce soil organic carbon (SOC) and increase soil N mineralization, but information on the level of tillage that increases net soil N mineralization and simultaneously maintains a considerable amount of SOC is poorly known. This study investigated the effect of four levels of tillage (15-cm deep by a local made plough) on net soil N mineralization rate (NMR), net nitrification rate (NNR), pools of NO(3)(-)-N and NH(4)(+)-N, and microbial biomass carbon (MB-C), water content of soil (WCS) and soil temperature (ST) in a Dystric fluvisols in the hot humid tropical climate of South Andaman Island of India. We hypothesized that: (1) tillage would increase NMR and reduce amount of SOC. But, these changes would depend on frequency of the tillage, i.e. greater would be the tillage frequency; higher, the NMR and decline in the amount of SOC; (2) low tillage would increase NMR, but reduce SOC nearly equal to short term zero tillage. Tillage levels included: (1) long term zero till (not tilled from 1983 to 2002; then from 2003 to 2006 crops (maize-okra rotation) were sown by dibbling, and weeds were cut and mulched), (2) frequent till (tilled three times before each crop sowing in the crop rotation from 1983 to 2002 and 2003 to 2006 as well; weeds were removed), (3)low till (not tilled from 1983 to 1999; then tilled once before each crop sowing in the crop rotation from 2000 to 2002 and weeds were removed; from 2003 to 2006 tilled like 2000-2002, but weeds were uprooted and buried in situ), and (4) short term zero till (from 1983 to 2002 tillage history was the same as in the low till; from 2003 to 2006 the crops were sown by dibbling in the crop rotation and weeds were cut and mulched in situ). Maize (Zea mays L.) was cultivated during wet season (WS, May to October) and okra (Abelmoschus esculentus L) during post-wet season (PWS, November to January) in all tillage treatments. Soils were sampled in all tillage treatments (levels) across the WS, PWS and dry (DS, February to April) seasons over two annual cycles (2004-2005 and 2005-2006) and analyses were done for the parameters investigated. We found that WCS was the highest (44-48%) during the WS and the lowest (10-16%) during the DS, however, ST was the lowest (25.5-26.5 degrees C) during the WS and the highest (30.5-33.4 degrees C) during the DS in all tillage treatments. Across the tillage levels, NMR increased from 1.06 to 1.96 mu g g(-1), day(-1) and NNR from 1.21 to 1.88 mu g g(-1) day(-1), and pools of NO(3)(-)-N and NH(4)(-)-N from 3.98 to 11.1 mu g g(-1) and 24.76 to 42.51 mu g g(-1), respectively. The increase was, however, the highest in the frequent till and the lowest in the long term zero till treatment. The NMR and NNR were the lowest (0.53-0.93.1 mu g g(-1), day(-1) and 0.49-0.86 mu g g(-1) day(-1), respectively) during the WS and the highest (1.09-1.71 mu g g(-1) day(-1) and 1.06-1.61 mu g g(-1) day(-1)) during the PWS in all tillage treatments. The NMR was positively correlated with the MB-C in all tillage treatments. Concurrent with the increase in the NMR, the SOC declined in all tillage treatments, but the decline was the highest in the frequent till and the lowest in the long term zero till treatment. Across the tillage treatments, the MB-C was correlated to the SOC. The SOC in the low till (7. 9 mg g(-1)) treatment was nearly equal to that in theshort term zero till treatment (8.8 mg g(-1)), but NMR was higher (0.86 mu g g(-1) day(-1)) particularly during the WS when plant's demand for N is usually high. Our results supported both the hypotheses, and suggested that low tillage might be a good option for soil fertility maintenance and carbon stock build-up in the soils of the hot humid tropics. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Meca, A. V.
    • Popescu, N.
  • Source: Annals of the University of Craiova - Agriculture, Montanology, Cadastre Series
  • Volume: 40
  • Issue: 2
  • Year: 2010
  • Summary: Within our country conditions the wheat, rye, barley, oilseed rape and pea-oat fodder are sown in autumn. They may be grown after crops that are harvested during summer or perennial crops or pastures that are included is crop rotation schemes. In the conditions of our country, crops that are harvested during the summer are: pea-oat fodder, pea, early potato, barley and wheat. After harvesting these crops, there must be done, immediately, the summer plowing because the soil is still moist, resulting a good quality plowing. Any delay conducts to diminishing the yields. Usually, the summer plow is made at 18-20 cm depth. Deeper plow are not necessary on most soil types from our country. Twenty cm deeper plow is need only on clayey soil that easily compacts, when the soil is highly infested by weeds, covered by high straw or when in the last year there was made a shallow plow. Summer plow, no matter the depth must be done along with harrow after plow. During the fall, till drilling, the soil has to be harrowed in order to destroy weeds and to maintain soil loosened.