• Authors:
    • Balkcom, K. S.
    • Gamble, B. E.
    • Patterson, M. G.
    • Reeves, D. W.
    • Price, A. J.
    • Arriaga, F. J.
    • Monks, C. D.
  • Source: Peanut Science
  • Volume: 34
  • Issue: 1
  • Year: 2007
  • Summary: Information is needed on the role of cover crops as a weed control alternative due to the increase in adoption of conservation-tillage in peanut production. Field experiments were conducted from autumn 1994 through autumn 1997 in Alabama to evaluate three winter cereal cover crops in a high-residue conservation-tillage peanut production system. Black oat ( Avena strigosa Schreb.), rye ( Secale cereale L.), and wheat ( Triticum aestivum L.) were evaluated for their weed-suppressive characteristics compared to a winter fallow system. Three herbicide systems were utilized: no herbicide, preemergence (PRE) herbicides followed by (fb) postemergence (POST) herbicides, and PRE fb sequential POST herbicides. The PRE fb POST herbicide input system consisted of pendimethalin at 1.12 kg ai/ha fb an additional early POST application of paraquat at 0.14 kg ai/ha plus bentazon at 0.56 kg ai/ha. The PRE fb sequential POST herbicide input system contained the aforementioned herbicides fb 2,4-DB at 0.22 kg ai/ha plus chlorimuron at 0.14 kg ai/ha applied late POST. No cover crop was effective in controlling weeds without a herbicide program. However, when black oat or rye was utilized with PRE fb POST herbicides, weed control was similar to the high input system in two out of three years. Yield increased in 14 of 27 comparisons following conservation-tilled peanut using the Brazilian cover crop management system, compared to a winter fallow system. Yields never decreased following a winter cover crop compared to winter fallow. The winter fallow, high herbicide input system yielded between 7 and 26% less peanut compared to the highest yielding system that included a winter cover crop. The Brazilian system using black oat or rye cover crop has potential to increase peanut productivity and reduce herbicide inputs for peanuts grown in the Southeast.
  • Authors:
    • Davey, M. R.
    • Pua, E. C.
  • Source: Transgenic crops IV
  • Year: 2007
  • Summary: This volume is part of a book series that reviews the progress in cell and tissue culture and genetic transformation methodologies, and presents aspects of the molecular genetics of target crops and the practical applications of transgenic plants. The first 3 volumes cover crop biotechnology before 2001, whereas the last 3 volumes deal with the more recent advances in this field. This book focuses on cereals, vegetables, root crops, herbs and spices. Section I (one chapter) is an introductory chapter that places into perspective the impact of plant biotechnology on agriculture. Section II (7 chapters) focuses on cereals (rice, wheat, maize, rye, pearl millet, barley and oats), whereas section III (7 chapters) covers vegetables (tomato, cucumber, aubergine, lettuce, chickpea, Phaseolus vulgaris and cowpea, carrot and radish). Root crops (potato, cassava, sweet potato and sugarbeet) are included in section IV (5 chapters), whereas herbs and spices (sweet and hot peppers, onion, garlic and mint) are presented in section V (3 chapters). This volume is an invaluable reference for plant breeders, researchers and graduate students in the fields of plant biotechnology, agronomy, horticulture, genetics, and plant and cell biology.
  • Authors:
    • Garcia, R.
    • Foloni, J.
    • Calonego, J.
    • Rosolem, C.
  • Source: PESQUISA AGROPECUARIA BRASILEIRA
  • Volume: 42
  • Issue: 8
  • Year: 2007
  • Summary: Potassium leaching from black oat ( Avena strigosa [ Avena nuda]) and pearl millet ( Pennisetum glaucum) straw as affected by simulated rainfall at different times after chemical desiccation was evaluated. Cover crops were grown in pots, in Botucatu, Sao Paulo, Brazil. Fifty days after emergence, the plants were sprayed with herbicide. The straw received simulated rains corresponding to 5 and 10 mm, considering a mulch of 8 t/ha, 3, 6, 9 and 15 days after desiccation. The amount of K leached from the plant residues increased after desiccation. Fifteen days after desiccation, a rainfall of 10 mm leached 11.1 kg/ha of K. A higher potential of black oat straw to leach K was observed with 10 mm of rain. The amount of K released by rains from black oat straw was greater than the pearl millet with 5 and 10 mm of rain, and this difference increased according to water loss from tissues.
  • Authors:
    • Mendez, M.
    • Vitti, M.
    • Costa, V.
    • Giacobbo, C.
    • Rufato, L.
    • Rossi, A.
    • Fachinello, J.
  • Source: Bragantia
  • Volume: 66
  • Issue: 3
  • Year: 2007
  • Summary: Field studies were conducted in Rio Grande do Sul, Brazil, to evaluate 5 different managements of black oat ( Avena nuda) crop cover. The treatments comprised: incorporation of black oat to soil; chemical management with herbicide; lodging; mowing at 5 cm; and control (uncovered soil). The sowing of the oat was accomplished by April of 2002 and the installation of the experiment by the end of August of the same year. The analysed variables were percentage of soil moisture at a depth of 15 cm, temperature of the soil at a depth of 5 cm, percentage of organic matter of the soil, soil resistance to the penetration and identification and degree of infestation by weeds. The data were submitted to analysis of variance through the F test and the averages compared by the Duncan Test. Maintenance of crop covering in orchards propitiated smaller temperature and larger soil moisture. The soil turn-over increased the diversity of weeds and the incorporation of black oat, after 60 days, had the same behaviour as the uncovered soil.
  • Authors:
    • Silva, P.
    • Ernani, P.
    • Sangoi, L.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 31
  • Issue: 3
  • Year: 2007
  • Summary: No-tillage systems, associated with black oat as preceding cover crop, have been increasingly adopted. This has motivated anticipated maize nitrogen fertilizer application, transferring it from the side-dress system at the stage when plants have 5-6 expanded leaves to when the preceding cover crop is eliminated or to maize sowing. This study was conducted to evaluate the effects of soil tillage system and timing of N fertilizer application on maize grain yield and agronomic efficiency of N applied to a soil with high organic matter content. A three-year field experiment was conducted in Lages, state of Santa Catarina, Brazil, from 1999 onwards. Two soil tillage systems were tested in the main plots: conventional tillage (CT) and no-tillage (NT). Six N management systems were assessed in the split-plots: S1, control (without N application); S2, all N (100 kg ha -1) applied at oat desiccation; S3, all N applied at maize sowing; S4, all N side-dressed when maize had five expanded leaves (V5 growth stage); S5, 1/3 of N rate applied at maize sowing and 2/3 at V5; and S6, 2/3 of nitrogen rate applied at maize sowing and 1/3 at V5. Maize response to the time and form of splitting N was not affected by the soil tillage system. Grain yield ranged from 6.0 to 11.8 t ha -1. The anticipation of N application (S2 and S3) decreased grain yield in two of three years. In the rainiest early spring season (2000/2001) of the experiment, S4 promoted an yield advantage of 2.2 t ha -1 over S2 and S3. Application of total N rate before or at sowing decreased the number of kernels produced per ear in 2000/01 and 2001/02 and the number of ears produced per area in 2001/02, resulting in reduced grain yield. The agronomic efficiency of applied N (kg grain increase/kg of N applied) ranged from 13.9 to 38.8 and was always higher in the S4 than in the S2 and S3 N systems. Short-term N immobilization did not reduce grain yield when no N was applied before or at maize sowing in a soil with high organic matter content, regardless of the soil tillage system.
  • Authors:
    • Chauhan, S. K.
    • Baljit, S.
    • Saralch, H. S.
  • Source: Agroforestry: systems and practices
  • Year: 2007
  • Summary: Punjab is the richest state in the country in term of per capita income and has earned the name as food bowl of the country by putting 84-85 per cent of its geographical area under highly intensive, technical and mechanical agriculture with cropping intensity as high as 185 per cent and contributing more than one third of rice and half of its wheat production to the central pool of food reserve. The food grain production in the state has increased approximately twelve times in a span of about 50 years after independence from 20 lac tones in 1950-51 to 234.89 lakh tonnes in 2002-2003. Achieving this high productivity without caring for natural resources has resulted in a considerable loss in the inherent production potential and deterioration of soil health. As a result, man is getting serious warning signals in the form of lowering of water table, drought, high rate of environmental pollution, extremes of climatic parameters, etc. Agriculture in the state has become too intensive, wasteful and reckless and the radical changes are required to maintain the balance. Therefore, there is a strong thinking to diversify farming in the state to maintain the sustainability of the whole system. The state government is stressing hard to save the natural resources through the diversification in traditional crop rotation and adopt resource-conserving measures. With the introduction of fast growing multipurpose tree species in Punjab during sixties, agroforestry has been recognized as a sustainable system of high potential to boost the state's meager forest resources and to check the further degradation of natural resources. Highly productive block planting of poplar intercropped with wheat, sugarcane, turmeric, oats, berseem, mustard, medicinal plants, seasonal flowers, vegetables, etc. has become popular in irrigated tracts of the state. Boundary planting of eucalypts in the wheat- paddy cropping system and scattered trees of kikar, khair, shisham, dek, etc. on cultivated lands under rainfed conditions, especially in the sub-montane foot hill zone, play an important role in soil conservation and boosting the socio-economic status of the farmers. These tree species have inherent potential of increasing the productivity of problematic lands of the state. Therefore, the diversion of farmlands towards agroforestry will not only increase tree cover but also achieve the desired objective of National Forest Policy-1988 and conserve the precious natural resources like ground water, soil, biodiversity, etc. and prove to be a viable alternative sustainable land use system, which is renewable and eco-friendly as compared to sole agricultural crops in the years to come. The profitability of tree plantations on farmers' fields will further improve with the implementation of trading of carbon credits under Kyoto Protocol.
  • Authors:
    • Rambo, L.
    • Strieder, M.
    • Argenta, G.
    • Suhre, E.
    • Silva, P.
    • Silva, A.
  • Source: Ciencia Rural
  • Volume: 37
  • Issue: 4
  • Year: 2007
  • Summary: The black oats use ( Avena strigosa) as species of soil covering in the winter, cause immobilization of the nitrogen (N), that reduces the plant development and grain yield of maize cultivated in succession. Thus, the black oat intercropped systems with leguminous as common vetch ( Vicia sativa) and brassicas as oilseed radish ( Raphanus sativus) is aimed at increasing nitrogen (N) disponibility in the system and the permanence timing of its residues in the soil. Two experiments were carried out in the growth seasons of 2001/2002 and 2002/2003, in Rio Grande do Sul, Brazil. The first one was aimed at evaluating the effect of three winter species of soil covering, grown as a single culture and as intercropped crops on maize grain yield, with and without nitrogen side-dressed. The second one was aimed at determining the most adequate seed ratio of oilseed radish and black oat in intercropped systems, as soil covering crops in the winter preceding maize, under different nitrogen levels side-dressed. In Experiment I, treatments were composed by N application of 180 kg ha -1, a control without N side-dressed and seven winter soil covering systems. In the Experiment II, treatments consisted of two levels of N side-dressing application in maize, a control without N side-dressed, and of three seed ratio of oilseed radish and black oat, as single and as intercropped crops and a control without crop in the winter. In all intercropped systems, independently of seed ratio used, the oilseed radish was mostly responsible for the yield of dry mass of the systems. The intercropped systems of common vetch or oilseed radish with black oat minimize the negative effect of oat on maize grain yield cultivated in succession in systems with low N availability and, even with high N supply, maize grain yield also increases when grown after common vetch.
  • Authors:
    • Souza, L.
    • Silva, D.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 6
  • Issue: 2
  • Year: 2007
  • Summary: Brazil has been producing maize in almost all regions, although the costs of production increased in the last years. New techniques which provide economy without yield loss can motivate producers, as maize is an important culture used at crop rotation system. Green manure may reduce maize production costs, maily to the incorporation of nitrogen. Data from an experiment were used for these comparisons; treatments were conducted in Mato Grosso do Sul, Brazil in three precedent maize cultures (black oat, oilseed radish and hairy vetch) and six nitrogen fertilizers levels (zero, 50, 100, 150, 200 and 250 kg/ha). Maize after black oat showed damage when N 25 kg/ha was used, while increasing levels increased yield up to 150 kg/ha, wherein the maximum yield was 1233 kg/ha. Maize after oilseed radish showed under zero rate a yield of 1500 kg/ha, but MEE occurs at N 40 kg/ha. Maize after hairy vetch showed no response to N, so MEE occurs at zero N, where yield was 2100 kg/ha. Maize antecessor cultures that release more nitrogen could provide higher yield to the system with lower use of fertilizers.
  • Authors:
    • Santen, E. van
    • Price, A.
    • Shaw, J. N.
    • Sullivan, D. G.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 6
  • Year: 2007
  • Summary: Conservation tillage is a commonly adopted best management practice for reducing runoff and erosion, and increasing infiltration. Yet current methodologies in place to monitor conservation tillage adoption are largely inappropriate for regional or national assessments. A major goal of this study was to evaluate the spectral response properties of four alternative winter cover crops using remotely derived crop residue cover indices. Experimental plots were located in east-central Alabama on a coarse-loamy siliceous, subactive, thermic Plinthic Paleudult. The experiment was a randomized complete block design having four replications of each of the following treatments: one fallow conventional tillage treatment and four no-tillage treatments with black oat ( Avena strigosa Schreb.), crimson clover ( Trifolium incarnatum L.), turnip ( Brassica rapa L. subsp.rapa), or rye ( Secale cereale L.) cover crops. Remotely sensed data were acquired three times using a 14 d sampling interval beginning near planting and using a handheld multispectral radiometer (485-1650 nm) in 2005 and 2006. Three crop residue cover indices using combinations of middle-infrared and visible spectra were compared and evaluated. Rye, clover, and black oat were spectrally similar, having an overall spectral response ranging from 8 to 45% (440-1650 nm). Increasing soil water content between remotely sensed data acquisitions was evidenced by as much as a 24% decline in middle-infrared reflectance. Despite this variability, a normalized difference ratio of middle-infrared (1650 nm) and blue (445 nm) spectra (Crop Residue Cover Index) provided the most consistent differentiation between tillage systems, varying within 8% of benchmark conditions (low soil water and low canopy cover). Considering the impact that conservation tillage may have on soil and water resources, rapid, watershed scale assessments of conservation tillage adoption may facilitate natural resource inventories, carbon sequestration estimates, and improved agricultural water management regimes.
  • Authors:
    • Mielniczuk, J.
    • Dieckow, J.
    • Zanatta, J.
    • Bayer, C.
    • Vieira, F.
    • He, Z.
  • Source: Soil & Tillage Research
  • Volume: 96
  • Issue: 1/2
  • Year: 2007
  • Summary: The carbon management index (CMI) is derived from the total soil organic C pool and C lability and is useful to evaluate the capacity of management systems to promote soil quality. However, the CMI has not been commonly used for this purpose, possible due to some limitations of the 333 mM KMnO 4-chemical oxidation method conventionally employed to determine the labile C fraction. We hypothesized, however, that physical fractionation of organic matter is an alternative approach to determine the labile C. The objectives of this study were (i) to assess the physical fractionation with density (NaI 1.8 Mg m -3) and particle-size separation (53 m mesh) as alternative methods to the KMnO 4-chemical oxidation (60 and 333 mM) in determining the labile C and thus the CMI, and (ii) to evaluate the capacity of long-term (19 years) no-till cropping systems (oat/maize: O/M, oat + vetch/maize: O + V/M, oat + vetch/maize + cowpea: O + V/M + C, and pigeon pea + maize: P + M) and N fertilization (0 and 180 kg N ha -1) to promote the soil quality of a Southern Brazilian Acrisol, using the CMI as the main assessment parameter. Soil samples were collected from 0 to 12.5 cm layer, and the soil of an adjacent native grassland was taken as reference. The mean annual C input of the cropping systems varied from 3.4 to 6.0 Mg ha -1 and the highest amounts occurred in legume-based cropping systems and N fertilized treatments. The C pool index was positively related to the annual C input ( r2=0.93, P