• Authors:
    • Callado, S.
    • Albino, J.
  • Source: Emirates Journal of Food and Agriculture
  • Volume: 24
  • Issue: 4
  • Year: 2012
  • Summary: The article is based on an agro-ecological evaluation of seven different agricultural systems in Teresopolis, Rio de Janeiro. The studied systems are dealing with: vegetable production system, ecological husbandry, cattle production system, sylvopastoral approaches as well as citrus cropping systems. The main objective is to evaluate the environmental impact of these systems using the "Emergy Analysis" as methodology. For this purpose, input data as materials, services, natural renewable/nonrenewable sources of 42 crops were analyzed. This method is based on energy flows, transforming all inputs and outputs in a common unit. This analysis allows comparisons across agricultural systems and their environmental impacts, as well as, makes possible the identification of scenarios to achieve greater sustainability. The main conclusions of this study are: the vegetable systems have large amounts of energy invested in irrigation, fertilizers and fuels; the largest value of sustainability corresponds to the ecological systems and it has the capacity to save capital in form of biomass in the system; cattle system causes bigger environmental damage and have the smallest yield per hectare in economic and energy terms; as for the citrus systems, a low investment rate was found and the use of renewable resources from this system is comparable to the vegetable systems.
  • 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:
    • 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.
  • Authors:
    • Fan, M. S.
    • Hao, Y. F.
    • Hu, B.
  • Source: China Vegetables
  • Issue: 10
  • Year: 2012
  • Summary: The effects of Chinese cabbage N application rate on Chinese cabbage yields, nitrogen utilization, nitrate contents, and nitrate nitrogen accumulation in soil were studied under potato-Chinese cabbage double cropping system in Hetao irrigated area of Inner Mongolia with 5 N application rates at Chinese cabbage planting season. The results showed that the yields and the double cropping net economic returns were the highest with the Chinese cabbage N application rate of 120 kg.hm -2; the double cropping system N accumulation and N recovery ratio were enhanced at the total N application rate from 225 kg.hm -2 to 405 kg.hm -2, compared with that of the conventional mono potato production in the open field at the N application rate of 225 kg.hm -2; the nitrate contents in Chinese cabbage and the nitrate accumulations within 0-160 cm soil profiles were increased with the increscent N applied rates. At the Chinese cabbage N application rate was ≥120 kg.hm -2, the nitrate contents in Chinese cabbage reached a high level, and the nitrate accumulations within 0-160 cm soil profiles were ≥162 kg.hm -2, hence the risk of nitrate contamination in underground water was increased for autumn irrigation. Reasonable N application rate had an effective effects on reducing nitrate contamination in groundwater, reducing nitrate content in Chinese cabbage, and increasing net economic return.
  • Authors:
    • Jennings, K. M.
    • Meyers, S. L.
    • Monks, D. W.
  • Source: Weed Technology
  • Volume: 26
  • Issue: 3
  • Year: 2012
  • Summary: Studies were conducted in 2008 and 2009 to determine the effect of S-metolachlor rate and application time on sweetpotato cultivar injury and storage root shape under conditions of excessive moisture at the time of application. S-metolachlor at 1.1, 2.2, or 3.4 kg ai ha -1 was applied immediately after transplanting or 2 wk after transplanting (WATP) to 'Beauregard', 'Covington', 'DM02-180', 'Hatteras', and 'Murasaki-29' sweetpotato. One and three d after S-metolachlor application plots received 1.9 cm rainfall or irrigation. S-metolachlor applied immediately after transplanting resulted in increased sweetpotato stunting 4 and 12 WATP, decreased no. 1 and marketable sweetpotato yields, and decreased storage root length to width ratio compared with the nontreated check. Sweetpotato stunting, no. 1 and marketable yields, and storage root length to width ratio in treatments receiving S-metolachlor 2 WATP were similar to the nontreated check. In 2008, Covington and Hattaras stunting 12 WATP was greater at 2.2 and 3.4 kg ha -1 (11 to 16%) than 1.1 kg ha -1 (1 to 2%). In 2009, S-metolachlor at 3.4 kg ha -1 was more injurious 4 WATP than 2.2 kg ha -1 and 1.1 kg ha -1. While cultivar by treatment interactions did exist, injury, yield, and storage root length to width ratio trends were similar among all cultivars used in this study.
  • Authors:
    • Fuller, M. P.
    • Al-swedi, F.
    • Al-Issawi, M.
    • Rihan, H. Z.
  • Source: Scientia Horticulturae
  • Volume: 141
  • Year: 2012
  • Summary: The effects of using PPM (plant preservative mixture) (Apollo Scientific Limited, UK) on the growth of cauliflower microshoots were determined. A negative correlation was found between the concentration of PPM in the liquid medium and the number of microshoots developed: the greater the concentration, the lower microshoot number. The stage of the culture process most suitable for the introduction of PPM was also investigated. While the use of PPM with blending medium (S23: 4.4 g L-1 MS + 30 g L-1 sucrose) did not control the later contamination in the culture medium, the use of 0.5 mL L-1 of PPM with culture medium (S23 supplemented with 2 mg L-1 (9.29 mu M) of kinetin + 1 mg L-1 (4.9 mu M) of IBA (indole butyric acid)) was found to be effective in controlling contamination and keeping the growth capacity of microshoots. Cauliflower microshoots were encapsulated in sodium alginate as artificial seeds. Artificial seeds conversion rate and viability assessed as fresh weights of plantlets produced were evaluated in different culture substrates (compost, perlite, sand and vermiculite). The effects of PPM concentrations used with S23 irrigation solutions were also evaluated. This study showed the effectiveness of using PPM in controlling the contamination and the necessity for determination the correct concentration and the correct stage for the use of this material in order to obtain optimum results. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Hussein, M. S.
    • Elsebai, M. N.
    • Rihan, M. K.
  • Source: Arab Universities Journal of Agricultural Sciences
  • Volume: 20
  • Issue: 1
  • Year: 2012
  • Summary: Egypt depends on the Nile River as a major source of water, it provides about 76.3% of its water requirements, other water sources provides about 23.7% of total water requirements. Agriculture sector is the main consumer of water in Egypt as it consumed about 85.9% of the total actual consumption of water in 2009. The main problem of the present paper is the decrease in the efficiency of water use in Egyptian agriculture. The objective of paper is to assess the efficiency of water use in agriculture in the old and new land Egypt through the use of partial efficiency measures. Results showed that in average of the cost of irrigation per feddan during the period (1998-2009), that was for winter crops in the old lands as follows: 85.3, 105.8, 119.3, 127.3 pounds/feddan for faba bean, sugar beet, alfalfa sustained, wheat at a cost of irrigation per feddan of which respectively. For summer crops in old land cost was about 114.7, 129.5, 139.8, 156.2, 217.8, 606.1 pounds/feddan at a cost of, sesame, soybean, peanut, corn, rice, sugar cane, respectively. For the winter crops in the new lands irrigation cost per feddan was about L.E 99.3, 169.0 for garlic and onion respectively. Summer crops in the new lands irrigation costs for watermelon, cucumber, potatoes, eggplant, peppers, and tomatoes were as follows: L.E 92.4, 133, 138.7, 139.8, 157.7, 194.3 pounds/feddan respectively. The results of the statistical analysis of partial-efficiency measures showed that, according to the criterion of net revenue from the water unit - winter crops on the old land as follows: alfalfa, wheat, faba bean, and sugar beet. As for the summer crops of old land the results showed of the statistical estimate of the partial-efficiency measures that peanuts, corn, sesame, sugar cane, rice, soybeans respectively. In the new lands the results of statistical analysis for the partial-efficiency measures, according to the standard net return of the water unit for winter crops were garlic followed by the first crop of onions. As for the summer crops, the results of statistical analysis of partial-efficiency measures, according to the standard net return of the water unit came summer crops in the new lands, were as follows: potatoes, tomatoes, watermelon, cucumber, eggplant, pepper. The results in general indicated the necessaries of reconsidering the present structure of cropping pattern to increase the efficiency of irrigation water use.
  • Authors:
    • Rodriguez-Delfin, A.
  • Source: Acta Horticulturae
  • Issue: 947
  • Year: 2012
  • Summary: Hydroponics has been used during years for research in the field of plant mineral nutrition and related topics. Today the soilless culture method is the most intensive horticulture production and is being applied with success in developed countries for commercial purposes. The growing and future of hydroponics in Latin America will much depend of the developing and adaptation of less sophisticated commercial systems. These have to be cost competitive with respect to the high sophisticated technology generated and used in developed countries, using natural and local substrates, developing native or endemic crops of the Region with economical potential for its high feed or medicinal value, among others. Meanwhile, as there is a considerable decreasing of agricultural soils in the world, soilless culture would be an important production alternative in urban and peri-urban areas, mainly in undeveloped countries. Inside the context of urban agriculture, hydroponics could be applied in the cities with more simple and low cost of technologies, mainly in extreme poverty areas, as a way to spread vegetables for self-consumption and to support the family or community income. Also to create micro-companies that will generate employments. There are no official statistics on the evolution of the state of the hydroponic cultures in Latin America. The main hydroponic systems used are the drip irrigation and NFT system. According with their profits, the main hydroponic crops are lettuce, tomato, pepper and strawberry. In Andean countries like Peru, Bolivia, Colombia and Ecuador, aeroponics is being developing to obtain basic potato tuber seed, free of virus. In relation to the media used in soilless culture, there is no ideal or optimum substrate, because a great diversity in media could be used, as pure or as mix form. Among the inorganic substrates it is possible to use quarry, river and quartz sand, gravel, pumice and tezontle. Husk rice, coco fiber, peat moss and sawdust are used as organic media. The use of rock wool is not generalized in the Region, but in countries like Mexico and Chile it is mainly used in tomato crop with drip irrigation system. Brazil and Mexico are the more representative hydroponic countries in Latin America. The area of soilless culture is increasing in the Region and every day there is much interest to learn and to dominate this technique of plants production without using soil. A great number of international courses, seminaries, congresses and symposia organized in countries like Peru, Mexico, Brazil, Costa Rica and Chile demonstrate this affirmation. Finally, it is necessary to obtain a hydroponic certification, as well as the organic products, to support the hydroponic growers in our countries.
  • Authors:
    • Hamilton, G.
    • Bickerton, M.
  • Source: Environmental Entomology
  • Volume: 41
  • Issue: 3
  • Year: 2012
  • Summary: Bell pepper plots intercropped with flowering plants were measured for improving biological control provided by natural enemies of the European corn borer [ Ostrinia nubilalis (Hubner)]. The intercropped plants Dill, Anethum graveolens L.; coriander, Coriandrum sativum L.; and buckwheat, Fagopyrum escuelentum Moench; were established on the edge of two pepper plots and compared with nonintercropped control plots. Predation by the three species Orius insidiosus Say; Coleomegilla maculata DeGeer; and Chrysoperla, sp. Stephens, was monitored by installing O. nubilalis egg masses on sentinel plants in 2008, 2009, and 2010. To assess negative impacts of alternative prey on O. nubilalis egg predation, green peach aphid, Myzus persicae (Sulzer) populations were monitored via whole-plant counts in 2009 and 2010. Myzus persicae densities on pepper plants peaked in June or July and then declined rapidly. Predation on O. nubilalis eggs increased rapidly after aphid populations declined. Aphid populations were reduced in two out of three field-seasons in intercropped plots. Seasonal predation by O. insidiosus was significantly higher in the intercropped system four out of five field-seasons and one field season by C. maculata. Results indicate that biocontrol of O. nubilalis can be improved by intercropping with flowering plants, although this capacity may depend on the abundance of alternative prey.