• Authors:
    • California Air Resources Board
  • Source: California Cap-and-Trade Regulation
  • Year: 2009
  • Authors:
    • Benbrook, C.
  • Source: Critical Issue Report: The First Thirteen Years
  • Year: 2009
  • Summary: Th is report explores the impact of the adoption of genetically engineered (GE) corn, soybean, and cotton on pesticide use in the United States, drawing principally on data from the United States Department of Agriculture. Th e most striking finding is that GE crops have been responsible for an increase of 383 million pounds of herbicide use in the U.S. over the first 13 years of commercial use of GE crops (1996-2008).
  • Authors:
    • McNeill, A.
    • Sommer, R.
    • Ibrikci, H.
    • Ryan, J.
  • Source: Advances in Agronomy
  • Volume: 104
  • Year: 2009
  • Summary: This review examines the varied aspects of N in the soils and cropping systems as reflected by research at The International Center for Agricultural Research in the Dry Areas (ICARDA) in Syria in collaboration with other countries of the West Asia-North Africa region, especially in Morocco and other countries north and south of the Mediterranean. The synthesis, therefore, reflects a broad overview of conditions that impinge an N nutrition of crops and the evolution of N research achievements since the advent of commercial fertilization over three decades ago. With few exceptions, the soils of the Mediterranean region are low in organic matter and consequently in the reserves of total N, thus posing a limit of growing crops without fertilizer N or biological N fixation (BNF) through legumes. Soil calibration studies established the value of the soil nitrate test as a predictor of crop response with field trials to establish application rates for the main crops. Applicability is influenced by depth of sampling and the extent of mineralization. Dryland crop responses to N varied widely throughout the region from 30 to 150 kg N ha -1, being dependent on soil N status and seasonal rainfall as the major determinant of yields. Splitting the N application was only advantageous in higher rainfall areas. Residual N from BNF by food and forage legumes influenced soil N supply for cereals and relative responses to N fertilizer. The contribution of rhizobia fixation to all the major legumes was quantified using 15N along with management factors that influenced BNF by legumes. Where legumes were newly introduced to a region, rhizobial inoculation was considered necessary. With cereal responses to fertilizer N, differences between varieties were highlighted. Where urea or ammonium-N fertilizers were used, volatilization was the main loss mechanisms rather than leaching or denitrification. Considerable work was done on N use within crop rotation systems and components of the N cycle defined along with inputs from urine and feces from grazing animals. Forage legumes were shown to enhance total soil N and both labile and biomass N, with the least influence from fallow. These N forms were shown to fluctuate during the year as moisture and temperature conditions changed. Fertilizer N use had a positive effect on grain quality with increased protein, as well as soil organic matter (SOM) and thus soil quality. The significant change of the gradual introduction of supplemental irrigation in traditional rainfed cropping areas and its implications for use of models to describe the complex nature of N in dryland cropping systems was described. With the likelihood of a continuation of intensification of the dryland cropping systems in the Mediterranean region, N fertilizer use will inevitably increase and along with it the need for greater use efficiency in the interest of production economics and the environment. While limited use has been made of modeling of N, this approach is likely to be of more significance in integrating the varied facets of N under Mediterranean cropping conditions.
  • Authors:
    • Paolo, E.
    • Garofalo, P.
    • Rinaldi, M.
  • Source: Crop & Pasture Science
  • Volume: 60
  • Issue: 3
  • Year: 2009
  • Summary: The aim of this work was to apply the CropSyst simulation model to evaluate the effect of faba bean cultivation as a break crop in the continuous durum wheat cropping system in southern Italy. The model was previously calibrated and validated for durum wheat and faba bean on data derived from experiments carried out in southern Italy (for different years and treatments), comparing observed and simulated crop growth, yield, soil water, and nitrogen output variables. The validation showed good agreement between simulated and observed values for cumulative above-ground biomass, green area index, and soil water content for both crops and grain yield for durum wheat; a negative correlation for grain yield in faba bean was observed due to a reduction in harvest index in the well-watered crop, which the model does not simulate well. Subsequently, a long-term analysis was carried out to study the effects on durum wheat of introducing a legume crop in rotation with the cereal in 2 and 3-year sequences. A long-term simulation, based on 53 years of daily measured weather data, showed that faba bean, due to a lower level of transpirated water (on average 247 mm for durum wheat and 197 mm for faba bean), allowed for greater soil water availability at durum wheat sowing for the cereal when in rotation with a legume crop (on average, +84 mm/m for durum wheat following the faba bean), with positive effects for nitrogen uptake, above-ground biomass, and grain yield of wheat. The yield increase of wheat when following a faba bean crop was on average +12%, but this effect was amplified in drier years (up to 135%). In conclusion, the case study offered the potential to confirm the positive results previously obtained in long/medium-term field experiments on the introduction of faba bean in rotation with durum wheat, as well as reduction in the chemical application of nitrogen.
  • Authors:
    • Patpour, M.
    • Dehghan, M.
    • Pouralibaba, H.
    • Pashapour, H.
    • Abediasl, G.
    • Soleymani, K.
    • Hesami, A.
    • Roohi, E.
    • Azimzadeh, S.
    • Nadermahmoodi, K.
    • Moayed, F.
    • Maleki, Y.
    • Eskandari, I.
    • Salekzanani, A.
  • Source: Seed and Plant
  • Volume: 25
  • Issue: 1
  • Year: 2009
  • Summary: Line Yesevi-93 (cultivar Abidar) was first introduced to Dryland Agricultural Research Institute (DARI) through the International Winter Preliminary Barley Yield Trials (IWPBYT) in 1994. It was selected as one the most high yielding lines based on observational and statistical trails (Regional Barley Yield Trials) carried out in different locations during 1997-2000. The average yield of Abidar cultivar in advanced trails was 2138 kgha -1 which was 5% and 34% higher than those of Sahand and local check cultivars, respectively. Yield stability analysis of data from grain yield of Abidar and other advanced lines of barley, using different methods, proved its high stability in different locations. It is a cold tolerant, early maturity, facultative type, drought tolerant and resistant to shattering cultivar. Its average height was 57 cm with 1000 kernel weight of 40-50 g. In on-farm yield trails, Abidar cultivar performed most better than the check cultivars. It is resistant to scald and powdery mildew diseases but susceptible to barley stripe. As this disease is seed-borne, it can easily be controlled through seed treatment by appropriate fungicides. Based on the advanced regional barley yield trials carried out in different cold and moderately cold regions of Iran, Abidar can be recommended for cultivation in moderate cold areas of Azarbaijan, Hamedan, Kurdistan, Zanjan, Ardebil, Ilam, Isfahan, Kermanshah, Chaharmahal-e-Bakhtiari, Markazi, Kohgilloyeh and Boyerahmad and Khorasan provinces in dryland conditions.
  • Authors:
    • Ghassemi-Golezani, K.
    • Raey, Y.
  • Source: New Zealand Journal of Crop and Horticultural Science
  • Volume: 37
  • Issue: 2
  • Year: 2009
  • Summary: Methodologies of competitive interaction quantification between crops are not widely investigated. Therefore, field experiments (using addition series) were conducted in 2005 and 2006, to quantify interspecific and intraspecific competition coefficients and, also, the relative competitive ability (RC) of potato ( Solanum tuberosum) and common bean ( Phaseolus vulgaris). The relations between potato tuber yield/plant and common bean density at various densities of potato and also with potato density at different densities of common bean are well described by the reciprocal equations. Potato tuber yield/unit area decreased as common bean density increased. Optimum potato densities on the basis of maximum potato tuber yield/unit area at 0, 20, 30, and 40 plants/m 2 of common bean were obtained at 14, 13, 12, and 12 plants/m 2, as estimated by the parabolic relations between potato tuber yield/unit area and potato densities at different common bean densities. Potato was a stronger competitor than common bean, as a potato plant was equal to 6.22 common bean plants, based on potato tuber yield. A common bean plant, also, was equivalent to 0.0475 of a potato plant, on the basis of common bean grain yield. Therefore, potato was more aggressive than common bean, indicating that potato tuber yield was mostly affected by intraspecific competition, whereas common bean grain yield was mostly affected by interspecific competition. Niche differentiation index (NDI) was smaller than 1, showing severe competition of two species for environmental resources. It was concluded that yield-density relations in intercropping could be well quantified by application of the proposed equations.
  • Authors:
    • Murari, S.
    • Masri, S.
    • Ryan, J.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 40
  • Issue: 1/6
  • Year: 2009
  • Summary: Recent concerns about the role of carbon (C) in climate change and the implications about soil organic matter (SOM) for sustainable use of soils have underlined the need to examine the role of SOM in cropping systems, particularly in fragile ecosystems. Accordingly, we examined the changes that occur in total SOM and in its more reactive fractions, labile and biomass C, within a long-term, cereal-based crop rotation trial. The rotations were wheat ( Triticum turgidum var durum) grown after vetch ( Vicia sativa), medic ( Medicago sativa), chickpea ( Cicer arietinum), lentil ( Lens culinaris), fallow, a summer crop, melon ( Citrullus vulgaris), and after wheat (i.e., continuous wheat). Secondary treatments involved nitrogen (N) fertilizer application and variable grazing intensity. Uncropped microplots were established in the main rotation plots, and in the fallow and medic ones with variable grazing. Total SOM and labile and microbial biomass C were periodically measured in the rotations throughout the cropping season. Medic and vetch were highest in the three C forms, with fallow always lowest. All forms changed with sampling time throughout the season. Organic matter decreased from 1.48% in February to 1.15% in August after cropping. Although labile C followed a similar pattern, with a large falloff between the May and August sampling, biomass C increased initially, remained stable for a few months, and decreased at the last two samplings. Although all three C forms were highest in the zero-grazing in the fallow and medic rotations, the effect of grazing was not significant. Thus, although organic C can be built up in the soil to varying extents depending on the crop rotation, it is a dynamic entity, especially the labile and biomass fractions, having implications for crop growth and soil quality.
  • Authors:
    • Murari, S.
    • Pala, M.
    • Masri, S.
    • Ryan, J.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 40
  • Issue: 1/6
  • Year: 2009
  • Summary: Mediterranean agriculture is mainly rainfed, with drought being the main crop production constraint, and is based on cereals, wheat ( Triticum spp), and barley ( Hordeum vulgare). Fallow was a traditional practice to conserve soil moisture, but because of land-use pressure it is giving way to cereal monoculture, which is unsustainable. The substudy reported here was part of a long-term rotation trial that sought to examine alternative crop rotation options, that is, durum wheat ( T. durum var durum) in rotation with fallow, summercrop (melon, Citrullus vulgaris), wheat (continuous cropping), chickpea ( Cicer arietinum), lentil ( Lens culinaris), vetch ( Vicia sativa), and medic ( Medicago spp). Ancillary treatments involved nitrogen (N) applied to the cereal phase and variable stubble grazing intensity (stubble retention, medium grazing, and heavy grazing or complete stubble removal). This substudy, conducted in the final 3 years of the 14-year trial, involved sampling soil and plants within the cropped rotation plots and sampling soil within bare microplots in selected larger rotation plots. We measured N forms in soil samples at different depths and throughout the seasons. Despite variation within and between seasons, the rotation effect of enhanced N was significant and consistent, being highest for vetch and medic, intermediate for chickpea and lentil, and least for continuous cereal, summer crop, and fallow. Therefore, legume-based cereal rotations can enhance soil N and thus save on N fertilizer. In bare microplots, total N decreased, labile N was inconsistent, mineral N increased, and biomass N increased and remained stable during the cropping season and then sharply declined. The nutrient dynamic data complemented the crop yield, water-use efficiency, and soil aggregation data from the trial to support the argument for using legumes in cereal rotations in place of fallow and continuous cereal cropping.
  • Authors:
    • Karayel, D.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 1
  • Year: 2009
  • Summary: The purpose of this research was to examine the performance of a modified precision vacuum seeder for no-till sowing of maize ( Zea mays L.) and soybean ( Glycine max L.) following wheat ( Triticum aestivum). A wavy-edged disc and side gauge wheels were fabricated and mounted to each unit of a common precision vacuum seeder (with a hoe opener on one row unit and a double disc-type opener on another row unit) and used to sow at three forward speeds (1.0, 1.5 and 2.0 m s -1). Multiple index, miss index, quality of feed index and precision of the distribution of the seeds along the length of the row, sowing depth uniformity, mean emergence time and percent emergence were determined. Sowing depth uniformity, mean emergence time and percent emergence of both maize and soybean seeds were decreased and precision of the distribution of the seeds along the length of the row was increased as a result of increasing forward speed. The distribution of the seeds along the length of the row, sowing depth uniformity and percent emergence of the seeder equipped with the double disc-type opener was better than the seeder equipped with the hoe-type opener. The precision of the distribution of the seeds along the length of the row for forward speeds of 1.0 and 1.5 m s -1 experienced in this study was well below 29%, and therefore is acceptable for both maize and soybean seeds. The modified precision vacuum seeder generally performed best using the double disc-type furrow opener at the forward speed of 1.0 m s -1, based on the distribution of the seeds along the length of the row, sowing depth uniformity, and percent emergence.
  • Authors:
    • Mastrorilli, M.
    • Katerji, N.
  • Source: European Journal of Agronomy
  • Volume: 30
  • Issue: 2
  • Year: 2009
  • Summary: The effect of soil texture on water use efficiency (WUE) was analyzed for six crops cultivated on loam and clay soils. Results were obtained after a long-term study, carried out in a lysimetric set-up, in conditions of experimental neutrality (climate, agro-techniques, and variety were the same for each crop) with the sole exception of the soil texture, which was the variable to be studied. In the case of potato, corn, sunflower, and sugar beet, WUE was reduced significantly when crops were grown in clay soil. The reductions ranged from 22% to 25%. The decrease of WUE in clay soil was coupled with significant reductions in yield and in ET, except in the case of the corn crop. The reduction in WUE in corn depended solely on the yield decrease. A 10% decrease in WUE values was also observed for the soy-bean and tomato grown in clay soil, but it was not statistically significant. Different causes which may reduce the WUE values observed in the clay soil are discussed. It seems coherent to hypothesize that, during the active growing phase, a deficit in water uptake occurs in the plants growing in the clay soil. This hypothesis is consistent with the observations of stomatal conductance, daily evapotranspiration, and leaf surface. In conclusion, the operative development of this study is outlined.