• Authors:
    • Hulugalle, N. R.
    • Ghadiri, H.
    • Weaver, T. B.
    • Harden, S.
  • Source: Chemosphere
  • Volume: 88
  • Issue: 3
  • Year: 2012
  • Summary: Organochlorine pesticides (OCPs) such as DDT and DDE have been detected in the surface 0.2 m of Vertisols in the lower Namoi Valley of north western New South Wales, Australia even though they have not been applied to crops since 1982. However, their presence in the deeper soil horizons has not been investigated. The objective of this study was to determine if OCPs were present to a depth of 1.2 m in Vertisols under irrigated cotton farming systems in the lower Namoi Valley of New South Wales. Soil was sampled from the 0-1.2 m depths in three sites, viz. the Australian Cotton Research Institute, ACRI, near Narrabri (149 degrees 36'E, 30 degrees 12'S), and two cotton farms near Wee Waa (149 degrees 27'E, 30 degrees 13'S) and Merah North (149 degrees 18'E, 30 degrees 12'S) in northern New South Wales, Australia. The OCPs detected and their metabolites were alpha-endo-sulfan, beta-endosulfan, endosulfan sulphate, DDD, DDE, DDT and endrin. The metabolite DDE, a breakdown product of DDT, was the most persistent OCP in all depths analysed. Endosulfan sulphate was the second most persistent followed by endrin > alpha-endosulfan > beta-endosulfan > DDT and DDD. DDT was sprayed extensively in the lower Namoi Valley up to the early 1980s and may explain the persistence of DDE in the majority of soil samples. Dicofol and Dieldrin. two OCPs previously undocumented in Vertisols were also detected. The movement of OCPs into the subsoil of Vertisols may occur when irrigation or rain transports soil colloids and organic matter via preferential flow systems into the deeper layers of a soil profile. Persistence of OCPs was closely correlated to soil organic carbon concentrations. The persistence in soil of OCP's applied to cotton crops grown more than two decades ago suggests that they could enter the food chain. Their presence at depths of 1.2 m suggests that they could move into groundwater that may eventually be used for domestic and stock consumption. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
  • Authors:
    • Ma, C. L.
    • Wang, P.
    • Guo, P.
    • Peng, H. Y.
    • Chen, L .S.
    • Yang, L. T.
  • Source: Scientia Horticulturae
  • Volume: 133
  • Year: 2012
  • Summary: 'Sour pummelo' ( Citrus grandis) seedlings were irrigated for 18 weeks with nutrient solution containing 0 (-Al) and 1.2 mM (+Al) AlCl 3.6H 2O * 0, 10 and 500 M sodium nitroprusside (SNP), a nitric oxide (NO) donor. Leaf malate content did not significantly change in response to SNP with or without aluminum (Al) except for an increase under 1.2 mM Al+10 M SNP, while leaf citrate content decreased with increasing SNP supply. Root malate content kept unchanging with or without Al except for an increase under 500 M SNP in the absence of Al, while SNP-treated roots had a higher or similar citrate content. Al decreased or did not affect malate content in roots and leaves, and citrate content in roots, but increased leaf citrate content. Al-treated roots and leaves displayed lower or similar activities of acid-metabolizing enzymes [phospho enolpyruvate carboxylase (PEPC), NAD-malate dehydrogenase (NAD-MDH), NADP-malic enzyme (NADP-ME), citrate synthase (CS), aconitase (ACO), NADP-isocitrate dehydrogenase (NADP-IDH), phospho enolpyruvate phosphatase (PEPP) and pyruvate kinase (PK)] except that they had higher or similar activities of NADP-ME and PK and Al-treated leaves had a higher or similar activity of PEPP. In conclusion, the OA metabolism in leaves and roots is differently affected by NO and Al interactions.
  • Authors:
    • Desneux, N.
    • Han, P.
    • Niu, C. Y.
    • Zhou, X. W.
  • Source: Journal of Economic Entomology
  • Volume: 105
  • Issue: 4
  • Year: 2012
  • Summary: The Chinese citrus fruit fly, Bactrocera minax (Enderlein) is a univoltine Tephritidae pest that infests Citrus species. Field trials were conducted in 2010 to determine the potential use of a lure based on enzymatical-hydrolyzed beer yeast as liquid bait (hereafter named H-protein bait) for B. minax in the Hubei province, China. In a citrus orchard, we compared the attractiveness among aqueous solutions of H-protein bait, GF-120 fruit fly bait, sugar-vinegar-wine mixture, torula yeast, and Jufeng attractant when used in traps and in spot sprays, that is, lures used in combination with the insecticide trichlorphon. The H-protein bait was the most attractive lure in traps, ensnaring significantly more adults than sugar-vinegar-wine mixture, torula yeast, and Jufeng attractant, in decreasing efficiency order. In spot sprays those with H-protein bait killed significantly more female and male flies within 40 min than those with sugar-vinegar-wine mixture, GF-120, Jufeng attractant, and the control. In addition, the total number of flies killed by H-protein bait during the spot spray duration was higher than other treatments. Our results demonstrated that the H-protein bait may be a useful tool in citrus orchards in China to monitor B. minax populations as well as to manage this pest when used in spot sprays.
  • Authors:
    • Vogt, G. A.
    • da Veiga, M.
    • Balbinot Junior, A. A.
    • Spagnollo, E.
  • Source: Ciência Rural
  • Volume: 42
  • Issue: 3
  • Year: 2012
  • Summary: The objective of this study was to evaluate in the fifth year of experimentation, the effect of winter soil uses on residual straw on the soil, physical and chemical soil attributes and grain yield of common bean cultivated in succession. An experiment was carried out in the North Plateau of Santa Catarina State, Brazil, from May 2006 to April 2011. Five winter soil uses were investigated: 1) multicropping with black oat + ryegrass + common vetch without grazing (multicropping cover); 2) the same multicropping, with grazing and 100kg ha(-1) of nitrogen year(-1), applied during the growing period (pasture with N); 3) the same multicropping, with grazing and without nitrogen fertilization (pasture without N); 4) oil seed radish, without grazing (oil seed radish); and 5) natural vegetation, without grazing (fallow). In the fifth year of experimentation, multicropping cover treatment inputted greater straw on the soil, but it was not observed expressive differences in soil attributes among the five winter soil uses. Cover crops, annual pasture and winter fallow did not affect the grain yield of common bean cultivated in succession.
  • Authors:
    • Pitelli, R. A.
    • Bianco, M. S.
    • Carvalho, L. B.
    • Bianco, S.
  • Source: Planta Daninha
  • Volume: 30
  • Issue: 1
  • Year: 2012
  • Summary: Soybean is one of the main crops in Brazil, but its productivity is very affected by weed competition. Two experiments were carried out in Jaboticabal, SP, Brazil, under greenhouse conditions to determine the accumulation and distribution of dry mass and macronutrients in soybean cv. BR-16, from October 2000 to February 2001, and Solanum americanum plants, from January to May 1995. Plants were grown in seven liter pots filled with river sand substrate and were daily irrigated with nutrient solution. The treatments were constituted by the times of samplings carried out at 14 day intervals, starting 21 days after emergence (DAE). Soybean evaluation was extended to 161 DAE, while S. americanum was extended to 119 DAE. The point of maximum theoretical accumulation of dry mass in soybean occurred at 104 DAE (35.00 g per plant) while for S. americanum, it occurred at 143 DAE (179.62 g per plant). From emergence until 49 and 63 DAE, leaves showed higher participation in dry mass accumulation of soybean and S. americanum, respectively. After these periods, an inversion could be observed, with leaves being surpassed by stems for the weeds, and by stems and later, by reproductive structures, for the crop. Macronutrient uptake rate reached higher values between 69 to 87 DAE for soybean and between 105 to 119 DAE for S. americanum. Considering the mean inflexion point values observed in soybean crop, at 75 DAE, it can be evidenced that one soybean plant theoretically accumulated 23.90 g of dry mass, 564.40 mg of N, 7.10 mg of P, 490.80 mg of K, 487.00 mg of Ca, 156.60 mg of Mg and 36.00 mg of S, while one S. americanum plant theoretically accumulated 33.75 g of dry mass, 875.96 mg of N, 88.46 mg of P, 983.54 mg of K, 647.60 mg of Ca, 100.93 mg of Mg, and 42.15 mg of S.
  • Authors:
    • Heinz, R.
    • Garbiate, M.
    • Tadeu Vitorino, A.
    • Viegas Neto, A.
    • de Sousa Mota, L.
    • Pereira Correia, A.
  • Source: Ciencia Rural
  • Volume: 41
  • Issue: 9
  • Year: 2011
  • Summary: This study aimed to evaluate the decomposition and nutrient release from crop residues of fodder radish and crambe in the implementation of no-tillage system. The experiment was conducted in a Distroferric Red Latossol with 762g kg(-1) of clay. The experimental design was randomized blocks with four replications. The treatments were applied in split plots, considering the species of cover crops (radish and crambe) as the main plots and harvest dates of decomposition bags (0, 15, 30, 45, 60, 75 days after management) as subplots. The cover crops were treated 60 days after management, in full bloom. Radish presented a dry mass production of 5586kg ha(-1) and crambe of 2688kg ha(-1). The kinetics of residue decomposition had a behavior similar to the dynamics of nutrient release, with an initial rapid phase followed by a slower one. The K, P and Mg are released more quickly for subsequent crops. The increased speed of nutrients release by crops occurred around 15 days after the biomass management.
  • Authors:
    • Hensley, M.
    • Bennie, A. T. P.
    • Botha, J. J.
    • Rensburg, L. D. van
  • Source: Water SA
  • Volume: 37
  • Issue: 5
  • Year: 2011
  • Summary: This review provides an overview of Water Research Commission (WRC)-funded research over the past 36 years. A total of 28 WRC reports have been consulted, 13 of these compiled by the University of the Free State, 4 by the University of Fort Hare, and the remainder mainly by the ARC-Institute for Soil Climate and Water. This work has resulted in extensive capacity building in this field - numerous technical assistants and 58 researchers have been involved, of which 23 are still active in research. The focus on the water flow processes in the soil-plant-atmosphere continuum (SPAC), with particular emphasis on processes in the soil, has greatly enhanced understanding of the system, thereby enabling the formulation of a quantitative model relating the water supply from a layered soil profile to water demand; the formulation of logical quantitative definitions for crop-ecotope specific upper and lower limits of available water; the identification of the harmful rootzone development effects of compacted layers in fine sandy soils caused by cultivation, and amelioration procedures to prevent these effects; and management strategies to combat excessive water losses by deep drainage. The explanation of the way in which SPAC is expressed in the landscape in the form of the ecotope has been beneficial with regard to the extrapolation of studies on particular SPACs to the large number of ecotopes where detailed studies have not been possible. Valuable results are reported regarding rainfall and runoff management strategies. Longer fallow periods and deficit irrigation on certain crop ecotopes improved rainfall use efficiency. On semi-arid ecotopes with high-drought-risk clay and duplex soils and high runoff losses, in-field rainwater harvesting (IRWH), designed specifically for subsistence farmers, resulted in maize and sunflower yield increases of between 30% and 50% compared to yields obtained with conventional tillage. An indication of the level of understanding of the relevant processes that has been achieved is demonstrated by their quantitative description in mathematical and empirical models: BEWAB for irrigation, SWAMP mainly for dryland cropping, and CYP-SA for IRWH. Five important related research and development needs are identified. The WRC has played, and continues to play, an important role in commissioning and funding research on water utilisation in agriculture and has clearly made an excellent contribution to the progress made in addressing the needs and requirements of subsistence, emergent and dryland farmers in South Africa.
  • Authors:
    • Hu, H.
    • Tian, S.
    • Zhong, W.
    • Li, Z.
    • Ning, T.
    • Wang, Y.
    • Zhang, Z.
  • Source: Scientia Agricultura Sinica
  • Volume: 44
  • Issue: 9
  • Year: 2011
  • Summary: Objective: The objective of this study was to understand the effects of normal urea and controlled release urea on grain filling rate, yield and water use efficiency of different maize cultivars under different tillage modes. Method: Three sets of treatments were arranged in a split-split plot design. The whole-plot treatment factor was the tillage mode, stubble ploughing or subsoiling after stubble ploughing. The subplot treatment factor was maize cultivars Zhengdan 958 and Denghai 3. The sub-subplot treatment factor was the nitrogen level, including applied with 225 kg N.hm -2 normal urea, applied with 225 kg N.hm -2 controlled release urea, and no nitrogen fertilizer used as control. Result: At the same tillage mode, nitrogen level and maize cultivars, the soil water content in 0-100 cm soil layer applied with controlled release urea was higher at pre-tasselling stage, while lower at maturity stage than those applied with normal urea. It indicated that treatment applied with controlled release urea could realize higher use of soil water through time and space, and as a result increased the gain filling rate and water use efficiency. Subsoiling after stubble ploughing could also increase the grain filling rate and water use efficiency. Compared with Zhengdan 958, Denghai 3 had higher grain filling rate, yield and water use efficiency. And these were positive coupling effects between urea type, subsoiling, and maize cultivars, which was benefit for higher yield in dryland farm. Conclusion: Higher use of soil water through time and space and higher grain filling rate were the important reasons for higher yield and water use efficiency. Using suitable maize cultivars and applying controlled release urea, with subsoiling after stubble ploughing, could make the good use of soil water, and realize the space-time coincide between soil water supply and crop needs, which will be the important measures to achieve higher grain yield and higher benefit in semi-humid region of China.
  • Authors:
    • Beasley, J. P.,Jr.
    • Tubbs, R. S.
    • Lee, R. D.
    • Grey, T. L.
    • Jackson, J. L.
  • Source: Peanut Science
  • Volume: 38
  • Issue: 1
  • Year: 2011
  • Summary: Most peanut ( Arahcis hypogaea L.) production occurs under highly intensive conventional tillage systems. With recent volatility in input prices, reducing tillage trips is a viable way of reducing production costs. However, growers can experience yield loss when switching from conventional tillage to strip-tillage in peanut on certain soil types due to the lack of an elevated bed at harvest time. Studies were conducted to compare standard strip-till with strip-till on two-row raised beds as well as rip and beds prepared in the fall. Comparisons were made on a coarse textured soil at Tifton, GA and a fine textured soil at Plains, GA. The three bed types, with and without wheat cover, were evaluated over two years at both locations. No effects of cover or interactions with bed type were present. At Plains, the rip and bed and raised bed reduced digging losses by 62 and 47%, respectively. Soil compaction within the harvest depth was reduced by 3.3 and 4.7 times by the raised bed and rip and bed, respectively compared to flat strip-till. The rip and bed increased peanut yield by 465 kg ha -1 over flat bed. At Tifton, no significant differences in yield or digging losses occurred between tillage methods. Soil compaction in the harvest depth was reduced by 1.9 and 2.5 times by raised bed and rip and bed, respectively on this coarse soil type. Reduced compaction and digging losses along with increased yield suggest bedding is more important on finer textured soils.
  • Authors:
    • Arnold, J. G.
    • Jin, V. L.
    • Johnson, M. V. V.
    • Haney, R. L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 141
  • Issue: 3-4
  • Year: 2011
  • Summary: The effects of biosolids application rate and history on soil potential C and N mineralization were measured over a 112-day laboratory incubation. Soils were collected from a large-scale biosolids recycling operation that surface-applies anaerobically digested Class B biosolids for commercial forage production. Five treatments were evaluated: unamended control; 22 Mg dry biosolids ha -1 y -1 applied for 25 years; 22, 45, and 67 Mg ha -1 y -1 applied for 8 years. Biosolids additions enhanced total soil organic C by 32-92% and total N by 30-157% compared to unamended soils. Total N increased with application rate and was dominated by nitrate-N. Potential C mineralization (cumulative CO 2 produced) was 11-62% greater in amended soils compared to controls and highest at 67 Mg ha -1 y -1. Net N mineralization and immobilization were highest early in the incubation for 45 and 67 Mg ha -1 y -1 treatments. No significant differences in potential C and N mineralization between controls and soils amended at the lowest rate for 8 or 25 years suggests that biosolids applications at 22 Mg ha -1 y -1 are sustainable over the long-term. Higher potential N mineralization rates and soil nitrate concentrations under higher application rates may increase the risk of off-site nutrient transport and requires further evaluation.