• Authors:
    • Freire, A.
    • Teixeira de Oliveira, M.
    • Alves de Oliveira, F.
    • de Medeiros, J.
    • de Oliveira, F.
  • Source: Revista Ciencia Agronomica
  • Volume: 43
  • Issue: 3
  • Year: 2012
  • Summary: This work was carried out to evaluate the effect of irrigation water at different salinity levels, and of seed treatment with plant growth regulator, on the development of the cotton plant. The experimental design used was completely randomized, arranged in a 5 x 2 factorial scheme with four replications. The treatments resulted from the combinations of five levels of salinity of the irrigation water (S-1-0.5, S-2-2.0, S-3-3.5, S-4-5.0 and 6.5 dS m(-1)) on seeds, both treated and not treated with growth regulator. The evaluated characteristics were: number of leaves, leaf area, height, dry mass of stems, leaves and vegetative parts, specific leaf area and leaf area ratio. There was an interaction between salinity and seed treatments with mepiquat chloride, but only for leaf area and leaf area ratio. All other characteristics decreased with the increasing salinity of the irrigation water, with greater reductions in leaf area (mean of 65.8%) and dry mass of vegetative parts (64%). Seed treatment with mepiquat chloride affected plant development, independent of salinity.
  • Authors:
    • Krutz, L.
    • Park, S.
    • Sij, J.
    • DeLaune, P.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 4
  • Year: 2012
  • Summary: Identifying management practices that conserve and protect water resources are very important to a wide variety of stakeholders within semiarid environments. The objective of this study was to develop water management strategies for transitioning tillage systems in cotton (Gossypium hirsutum L.) production within the Texas Rolling Plains when in a subsurface drip irrigation (SDI) system. Five irrigation regimes (0, 33, 66, 100, and 133% evapotranspiration [ET] replacement) and four tillage systems (conventional till, reduced till, no-till, and no-till with a terminated cover crop) were evaluated. The study was conducted for 3 yr and treatments were replicated three times in a randomized complete block design. Lint yields were not affected by the main effects of tillage or the interaction of tillage and ET replacement. In contrast ET replacement was a significant factor for lint yields, irrigation water use efficiency, and net returns. Greatest lint yields and net returns were achieved at 100% ET replacement. Fitted models indicated that optimum lint yields and net returns were achieved at 104.5% ET and 102% ET, respectively. Irrigation at 83% ET was within the 95% confidence interval for lint yield. Net returns were significantly higher for no-till systems compared with conventional till. Thus, adoption of conservation tillage systems should not negatively affect lint yield or net returns in deficit irrigated SDI cotton systems within the Texas Rolling Plains, particularly during the transition from intensively tilled systems to conservation tilled systems.
  • Authors:
    • de Figueiredo, M.
    • Figueiredo, M.
    • Detomini, E.
  • Source: Revista de Politica Agricola
  • Volume: 21
  • Issue: 1
  • Year: 2012
  • Summary: The main purpose of this study is to identify the optimum allocation of limited amount of land and irrigation water across a number of alternative farm enterprises, maximising the whole-farm profitability by considering present relative prices, changes in river water availability, irrigation system efficiency and a highly variable climate. It was developed an optimisation model by using linear programming language to maximise the whole-farm profit of farm located in Wee Waa (NSW, Australia), for three different scenarios (dry, average and wet years) over two seasons. The whole-farm profit is highly sensitive to climate variability and also to prices and yields variability, especially in relation to cotton.
  • Authors:
    • Lamers, J.
    • Djanibekov, N.
    • Khamzina, A.
    • Djanibekov, U.
  • Source: Forest Policy and Economics
  • Volume: 21
  • Year: 2012
  • Summary: This study analyzed the financial attractiveness of Clean Development Mechanism Afforestation and Reforestation (CDM A/R) in irrigated agricultural settings. The Net Present Value (NPV) and Internal Rate of Return (IRR) of CDM A/R were estimated by analyzing the case of Khorezm region in Uzbekistan, where a mixed-species tree plantation was established on marginal cropland. The dual purposes of carbon sequestration and production of fruits, leaves as fodder, and fuelwood were studied over a seven-year rotation period. We compared the opportunity costs of land in marginal agricultural areas between this short-rotation plantation forestry and the annual cultivation of the major crops in the region, i.e., cotton, winter wheat, rice, and maize. The analyses were performed considering different levels of irrigation water availability, from 0 to 30,000 m(3)/ha, to reflect the reality of a high variability of water supply in the region. The NPV of CDM A/R ranged between 724 and 5794 USD/ha over seven years, depending on the tree species. Among the latter, Elaeagnus angustifolia L had the highest profits due to the annually recurring cash flows generated from fruit production. Temporary Certified Emission Reductions (tCER) ranged within 399-702 USD/ha after the assumed 7-year crediting period and would not suffice to cover initial investments and management costs of tree plantations. IRR peaked at 65% with E. angustifolia under the conventional afforestation and measured - 10% and 61% when considering only the tCER and the CDM A/R, respectively. In contrast, other species had higher IRRs in case of the CDM A/R. The total profits from tree plantations exceeded those of both cotton and winter wheat, even with the assumption that there was an optimal irrigation supply for these crops. Rice production was overall the most profitable land use option but required water input of 26,500 m(3)/ha/year, which is not consistently available for marginal croplands. We argue that the current global average price of 4.76 USD/tCER is insufficient to initiate forestry-based CDM projects but, in the absence of other incentives, can still motivate forestation of degraded croplands for land rehabilitation and the provisioning of non-timber products. Given the low irrigation needs of trees, 3-30% of the crop water demand, a conversion of degraded cropland to forested areas could save up to 15,300 m3/ha/year at the current tCER price. Combining the monetary value of water and carbon would enlarge the scope for CDM A/R in irrigated drylands, thus enhancing the investments in marginal land rehabilitation and strengthening the resilience of rural populations to the repercussions of climate change. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Dong, H.
    • Dong, H.
  • Source: Australian Journal of Crop Science
  • Volume: 6
  • Issue: 2
  • Year: 2012
  • Summary: Soil salinity is a major threat to cotton production worldwide. Excessive salt in the soil leads to a series of physiological and biochemical metabolic disorders in cotton plants mainly as a result of osmotic effects (dehydration), nutritional imbalance and toxicity of salt ions (Na + and Cl -). The metabolic disorders may finally reduce plant growth and lint yield and quality, particularly in conditions of high salinity. Basically, combating the effects of salinity stress on cotton plants involves two main strategies: one is to improve salt tolerance through genetic breeding and chemical or biological treatment, the other is to avoid or alleviate salinity stress by improving at least part of the root-zone environment. This review highlights the technologies for combating salinity stress on cotton, with a focus on recent advances in agronomic techniques for managing salinity in the root zone. We recommend a comprehensive use of agronomic practices such as suitable cultivars, proper irrigation and fertilization, seed pretreatment, furrow seeding, plastic mulching and induction of unequal salt distribution in the root-zone to combat salinity stress. Further research should focus on exploration and understanding of the uptake and efficient use of water and nutrients in saline soils. Research should also focus on the development of new products for cotton growing in saline soils like new foliar and specific slow-release fertilizers and commercial plant growth regulators to improve salt tolerance.
  • Authors:
    • Li, D.
    • Zhang, T.
    • Li, X.
    • Zhang, Z.
    • Chen, J.
    • Wang, H. J.
    • Hou, Z. A.
    • Lv, X.
    • Dong, N.
    • Li, D.
    • Zhang, T.
    • Li, X.
    • Zhang, Z.
    • Chen, J.
    • Wang, H.
    • Hou, Z.
    • Lv, X.
    • Dong, N.
  • Source: Xinjiang Agricultural Sciences
  • Volume: 49
  • Issue: 4
  • Year: 2012
  • Summary: Objective: The purpose of this project was to explore the influence of different irrigation water amounts on cotton growth and yield under film mulch drip irrigation basing on Penman-Monteith formula. Method: Basing on Penman-Monteith formula, a plot experiment was carried out according to a certain gradient of the irrigation amount combining with meteorological data and soil moisture to analyze the changing regularity of dry matter accumulation, water consumption, and discuss the relationship among dry matter accumulation, yield and water consumption. Result: Dry matter accumulation of cotton in different growth stages complies with the "S" type changing regularity. The soil moisture content is basically at the suitable condition of water requirement in each cotton growth stage according to the recommend irrigation water amount basing on Penman-Monteith formula, and soil moisture was fully made use of and the goal of water-saving without influencing cotton growth was achieved. The daily average transpiration of cotton presented "low-high-low" tendency in the whole growth stage. The fitting result of dry matter accumulation and water consumption ( R=0.857 8) showed that there was a significant correlation between them. The regression model was established with seed cotton yield ( Y) and irrigation amount ( X): Y=-0.010 8 X2+7.906 9 X-1 029.9 ( R2=0.926 2). Conclusion: The irrigation amount based on the theory of Penman formula basically met the cotton water requirement of each growth stage.
  • Authors:
    • Cherif, S.
    • El-Ayni, F.
    • Jrad, A.
    • Trabelsi-Ayadi, M.
  • Source: Water Environment Research
  • Volume: 84
  • Issue: 8
  • Year: 2012
  • Summary: Groundwater is the main source of water in Mediterranean, water-scarce, semiarid regions of Tunisia, Africa. In this study of the Korba coastal aquifer, 17 water wells were studied to assess their suitability for irrigation and drinking purposes. Assessment parameters include pH, salinity, specific ion toxicity, sodium adsorption ratio, nutrients, trace metals pollutants, and fecal indicators and pathogens. Results indicate that salinity of groundwater varied between 0.36 dS/m and 17.4 dS/m; in addition, its degree of restriction is defined as "none", "slight to moderate", and "severe" for 18, 23, and 59% of the studied wells, respectively. To control salts brought in by irrigation waters, the question arises as to how much water should be used to reach crop and soil requirements. To answer this question, a new approach that calculates the optimum amount of irrigation water considering the electrical conductivity of well water ( ECw), field crops, and the semiarid meteorological local conditions for evapotranspiration and rainfall is developed. This is applied to the authors' case study area; barley and lettuce were selected among the commonly grown crops because they are high- and low-salinity tolerant, respectively. Leaching requirements were found to be independent of the crop selected, and depend only on the season, that is, 250 to 260 mm/month in the driest season, with a minimum of 47 mm/month though all seasons. A high bacteriological contamination appears in almost all samples. However, if disinfected and corrected for pH, all the well waters can be used for animal farming (including livestock and poultry), although only 29% could be used for human consumption.
  • Authors:
    • Chehbouni, A.
    • Lepag, M.
    • Jarlan, L.
    • Ezzahar, J.
    • Erraji, T.
    • Khabba, S.
    • Er-Raki, S.
    • Hanich, L.
  • Source: Acta Horticulturae
  • Issue: 951
  • Year: 2012
  • Summary: Sap flow measurements based on heat balance method gives a direct measurement of the mass flow rate of sap in the stem. However, extrapolation of these measurements from the stem to the field scale is an important challenge. In this study, 15 branches of citrus trees with different diameters were equipped with Dynamax sap flow gauge. These individual branch measurements have been after extrapolated to the canopy transpiration by using two up-scaling methods. The first one uses the relationship between sap flow and branches diameter and the second one uses the distribution of the branch diameter in the orchards. The results showed a good agreement between the two methods estimates (R 2=0.95). A comparison between scaled-up transpiration from sap flow and measured evapotranspiration (ET ed) by eddy covariance showed an average daily difference of about 0.87 mm/day which represents 25% of ET ed. This substantial amount of water was lost through soil evaporation and part of it could be saved by improving the drip irrigation management.
  • Authors:
    • Frisvold, G. B.
    • Konyar, K.
  • Source: Water Resources Research
  • Volume: 48
  • Issue: 5
  • Year: 2012
  • Summary: This study examined how agriculture in six southwestern states might adapt to large reductions in water supplies, using the U.S. Agricultural Resource Model (USARM), a multiregion, multicommodity agricultural sector model. In the simulation, irrigation water supplies were reduced 25% in five Southern Mountain (SM) states and by 5% in California. USARM results were compared to those from a "rationing" model, which assumes no input substitution or changes in water use intensity, relying on land fallowing as the only means of adapting to water scarcity. The rationing model also ignores changes in output prices. Results quantify the importance of economic adjustment mechanisms and changes in output prices. Under the rationing model, SM irrigators lose $65 in net income. Compared to this price exogenous, "land-fallowing only" response, allowing irrigators to change cropping patterns, practice deficit irrigation, and adjust use of other inputs reduced irrigator costs of water shortages to $22 million. Allowing irrigators to pass on price increases to purchasers reduced income losses further, to $15 million. Higher crop prices from reduced production imposed direct losses of $130 million on first purchasers of crops, which include livestock and dairy producers, and cotton gins. SM agriculture, as a whole, was resilient to the water supply shock, with production of high value specialty crops along the Lower Colorado River little affected. Particular crops were vulnerable however. Cotton production and net returns fell substantially, while reductions in water devoted to alfalfa accounted for 57% of regional water reduction.
  • Authors:
    • Blanco-Lopez, M. A.
    • Perez-Rodriguez, M.
    • Garcia-Cabello, S.
    • Lopez-Escudero, F. J.
  • Source: European Journal of Plant Pathology
  • Volume: 133
  • Issue: 4
  • Year: 2012
  • Summary: Verticillium dahliae Kleb. causes Verticillium wilts in many herbaceous and woody species. Many hosts of the pathogen are commonly cultivated in Andalucia (southern Spain), particularly major crops such as cotton, vegetables, almond, peach and, particularly, olive, in which the fungus causes Verticillium wilt of olive. Infective structures of the pathogen (microsclerotia), produced in the late phases of the infection cycle in senescent tissues of the infected plants, can be spread over short or long distances by a number of dispersal methods. Irrigation water is one of the factors implicated in this spread of V. dahliae. Indeed, increasing irrigation dosages in crops or an inadequate irrigation schedule have been identified as cultural practices favouring Verticillium wilt onset and severity in olive and other hosts. Most of the cultivated areas in the Guadalquivir Valley of Andalucia are irrigated by pumping stations using modern infrastructures that supply water to thousands of hectares of farm land, which are usually associated with irrigation communities. This study demonstrates that the pathogen survives in the sediment and particles suspended in water used for irrigation in different facilities of an irrigation community, that were involved in distributing water (main canal and reception tank of a investigated pumping station, irrigation pools and sand from filters). Thus microsclerotia moves from the pumping station to individual plots (olive and cotton cultivated farm) as viable microsclerotia, free or embedded in soil particles and plant debris, suspended in the irrigation water, or deposited in the sludge in piping systems or water storage ponds. We have detected amounts of inoculum in the solid pellet samples in these facilities that ranged from 2.7 to 6.7 microsclerotia per gram. Besides this, water from drippers in cultivated plots released into the soil a variable amount of infective propagules of the pathogen over time that accounted for 3.75 microsclerotia/m 3 in some of the recording times. Therefore, irrigation water becomes an important source of inoculum that is very effectively involved in medium and long-distance spread of the pathogen.