• Authors:
    • Gabriel, J. L.
    • Quemada, M.
  • Source: European Journal of Agronomy
  • Volume: 34
  • Issue: 3
  • Year: 2011
  • Summary: Cover crops in dry regions have been often limited by low nutrient and water-use efficiency. This study was conducted during 3.5 years to determine the effect of replacing bare fallow by a cover crop on yield, N uptake, and fate of labeled fertiliser in an intensive maize production system. Three treatments were studied: barley ( Hordeum vulgare L.), vetch ( Vicia villosa L.) and bare fallow during the intercropping period of maize ( Zea mays L.). All treatments were irrigated and fertilised following the same procedure, and a microplot in each plot was established with 210 kg N ha -1 of double labeled ammonium nitrate. Crop yield and N uptake, soil mineral N (N min), and recovery of 15N in plant and soil were determined after maize harvest and killing the cover crop. Replacing bare fallow with cover crops did not affect subsequent maize yield but affected N uptake. Vetch increased N supply by legume residues after the second year, and the N content in grain by the third. Nitrogen recover from fertiliser was not affected by treatment and averaged 46%. Barley recovered more 15N during the autumn-winter period than vetch or fallow. Under representative conditions, average barley N content was 47, vetch 51, and spontaneous vegetation content 0.8 kg N ha -1. Recovery of 15N in barley comprised 19% of total N content in aerial biomass, while only 4% in vetch. Vetch enhanced soil 15N recovery more than other treatments, suggesting its presence in a fairly stable organic fraction unavailable for maize uptake or lost. Replacing bare fallow by a cover crop only reduced fertiliser losses in a year with abundant precipitation. Nevertheless, reduction in soil N min in vetch and bare fallow treatments was similar, showing that N losses can be reduced in this cropping system, either by replace bare fallow with barley or smaller N fertiliser application to maize.
  • Authors:
    • Germana, C.
    • Intrigliolo, F.
    • Giuffrida, A.
    • Stagno, F.
    • Continella, A.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: During three consecutive years, in a citrus orchard planted with Tarocco 'Meli' and 'Scire' on sour orange ( C. aurantium L.) were verified the differences of the plant water status and the possibility to build an empirical model to estimate the psi pd utilizing stem water potential (psi md) and vapor pressure deficit (VPD md) measured at midday. The first results showed statistical differences during the irrigation season in the two clones water potential. These difference permitted to separate the data of Tarocco 'Meli' and 'Scire'. As a result, two empirical models were built. The 2nd degree equation (Psi pd=a+b 1Psi md+b 2VPD md) was obtained by considering the Psipd as dependent variable, the Psi md and the VPD md as explanatory variables. ANOVA applied to the multiple regression resulted highly significant with P-value
  • Authors:
    • Sungur, S.
    • Sangün, M. K.
  • Source: Food Chemistry
  • Volume: 126
  • Issue: 1
  • Year: 2011
  • Summary: Recently, the exposure to perchlorate was emphasised as an important risk factor for human and especially newborn health. A number of studies were focused on this matter. In this study, samples of soil, vegetable (cabbage, spinach, lettuce, carrot, tomato, red cabbage), fruit (orange, mandarin, lemon, grapefruit), water, milk and fish were taken from 8 different regions of Hatay (Samandag, Krkhan, Reyhanl, Amik Plain, Dortyol, Yayladag, Altnozu, Erzin). An ion chromatography system (Shimadzu C196-E039A model) was used to determine the concentrations of perchlorate in the samples. 2.5 mM Phthalic acid and 2.4 mM tris (hydroxymethyl)aminomethane solutions (pH=4) were used as the mobile phase. A flow rate of 1.5 ml min -1 and oven temperature of 40°C were used during the analysis. The foods had perchlorate concentrations in the range of 0.236-1.218 g kg -1. The perchlorate concentration varied from 0.300.01 to 0.940.02 g l -1 in milk samples. Perchlorate concentrations were determined to be lower in the drinking waters (0.440.03 g l -1) compared to irrigation waters (0.590.03 g l -1). Perchlorate concentrations of the fish samples were ranged from 0.380.01 to 0.610.01 g kg -1.
  • Authors:
    • Puig, R.
    • Rius, A.
    • Riba, J.-R.
    • Esteban, B.
    • Baquero, G.
  • Source: Biomass and Bioenergy
  • Volume: 35
  • Issue: 8
  • Year: 2011
  • Summary: The use of straight vegetable oil (SVO) as biofuel has been recognized as a valid substitute of diesel fuel in the agricultural sector under specific circumstances. Its direct use reduces most of the chemical processes involved when converting it into biodiesel, thus lowering harmful emissions. This study presents the economic analysis of a self-supply farming model that uses rapeseed as its fuel base. This model addresses agricultural environmental concerns and can even minimize dependence on the fluctuating costs of diesel fuel. The use of SVO in agriculture can help reduce farmers' vulnerability to fossil fuel prices. The economic evaluation of the model proposed in this study shows clear economic benefits of introducing rapeseed to the traditional crop rotation of wheat and barley. The key factors analyzed in this model are diesel fuel price, diesel fuel grants and crop aids. The current situation in Spain favors the use of diesel fuel in agriculture rather than rapeseed SVO due to an 8% profit difference. However, results show that changes in key factors slightly affect the profit margin, calculating a difference of only 3.7% for particular factor combinations. Combined environmental-friendly agriculture supporting policies are necessary to cover this slight profit difference to promote this biofuel. (C) 2011 Elsevier Ltd. All rights reserved.
  • Authors:
    • Wallender, W. W.
    • Burger, M.
    • Horwath, W. R.
    • Mailapalli, D. R.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 1
  • Year: 2010
  • Summary: Farming practices, including tillage, cover cropping and residue management can have profound effects on the efficiency of irrigation practices. The effects of three field management practices (FMPs) standard tillage and winter-fallow (ST), standard tillage and winter-cover crop (STCC), and no-till and winter-fallow (NT) and two field lengths (122 and 366 m) on runoff and export of dissolved organic carbon (DOC) were investigated in a furrow-irrigated cropping system over two years. The residue cover was 40, 32 and 11% in 2007, and 58, 61 and 11% in 2008 for STCC, NT and ST, respectively. Furrow irrigation experiments were conducted prior to crop planting following the cover crop. The inflow was kept constant across all treatments, and infiltration and runoff were estimated using a volume balance model (VBM). The DOC concentration tended to increase with increasing field length, but did not differ among the FMPs. A threefold increase in field length increased infiltration by 40%, and decreased runoff by 60-90% and DOC export by 65-83%. In both years, infiltration was highest in STCC. In NT, infiltration was lowest in 2007, which was likely due to soil sealing, and intermediate among the three FMPs in 2008 perhaps due to the increase in residue cover in the second year. The DOC budget analysis showed that fields and FMPs acted as DOC sinks exporting less DOC than was applied in the irrigation water. The results suggest that longer furrows and STCC were greater DOC sinks compared to ST and shorter field practices. The VBM, as applied in this study to estimate infiltration and runoff, could be used to predict optimal field length to minimize runoff and promote DOC adsorption to soil within the constraints of water quality and availability and soil conditions.
  • Authors:
    • Maggini, R.
    • Carmassi, G.
    • Campiotti, C. A.
    • Pardossi, A.
    • Massa, D.
    • Incrocci, L.
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 7
  • Year: 2010
  • Summary: In the spring-summer season of 2005 and 2006, we explored the influence of three fertigation strategies (A-C) on the water and nitrogen use efficiency of semi-closed rockwool culture of greenhouse tomato conducted using saline water (NaCl concentration of 9.5 mol m -3). The strategies under comparison were the following: (A) crop water uptake was compensated by refilling the mixing tank with nutrient solution at full strength (with the concentrations of macronutrients equal or close to the corresponding mean uptake concentrations as determined in previous studies) and the recirculating nutrient solution was flushed out whenever its electrical conductivity (EC) surpassed 4.5 dS m -1 due to the accumulation of NaCl; (B) the refill nutrient solution had a variable EC in order to maintain a target value of 3.0 dS m -1; due to the progressive accumulation of NaCl, the EC and macronutrient concentrations of the refill nutrient solution tended to decrease with time, thus resulting in a progressive nutrient depletion in the recycling water till N-NO 3- content dropped below 1.0 mol m -3, when the nutrient solution was replaced; (C) likewise Strategy A, but when EC reached 4.5 dS m -1, crop water uptake was compensated with fresh water only in order to reduce N-NO 3- concentration below 1.0 mol m -3 before discharge. In 2005 an open (free-drain) system (Strategy D), where the plants were irrigated with full-strength nutrient solution without drainage water recycling, was also tested in order to verify the possible influence of NaCl accumulation and/or nutrient depletion in the root zone on crop performance. In the semi-closed systems conducted following strategies A, B or C, the nutrient solution was replaced, respectively, 10, 14 and 7 times in 2005, and in 19, 24 and 14 times in 2006, when the cultivation lasted 167 days instead of 84 days in 2005. In both years, there were no important differences in fruit yield and quality among the strategies under investigation. Strategy C produced the best results in terms of water use and drainage, while Strategy B was the most efficient procedure with regard to nitrogen use. In contrast to strategies A and D, the application of strategies B and C minimized nitrogen emissions and also resulted in N-NO 3- concentrations in the effluents that were invariably lower than the limit (approximately 1.42 mol m -3) imposed to the N-NO 3- concentration of wastewater discharged into surface water by the current legislation associated to the implementation of European Nitrate Directive in Italy.
  • Authors:
    • Silva, J. R. M. da
    • Silva, L. L.
    • Pisco, A. M. V.
    • Torres, C. J. V.
  • Source: International Conference on Agricultural Engineering
  • Year: 2010
  • Summary: Centre-pivot irrigation systems frequently cause surface runoff and erosion problems. This is more evident in complex topographies and low infiltrability soils. To overcome these problems farmers have tried different tillage systems, attaining different results, depending on soil type and irrigation management. Field tests, using small plots, were carried out in a Mediterranean soil with three different tillage systems: no-till, basin tillage and conventional tillage, as a control practice. Conventional tillage showed the highest runoff values (30% of collected water depth) with significant differences to no-till (15%) and basin tillage (2%). Maximum average values of sediment yields per irrigation event were lower for basin tillage (4.46 kg/ha) and no-till (9.59 kg/ha) compared to conventional tillage (23.45 kg/ha). The no-till system showed higher soil water content along all the irrigation season compared to the other two tillage systems. From a soil and water conservation point of view the basin tillage practice is the best option. But, from an economic point of view the no-till practice can be also a good option in these conditions.
  • Authors:
    • Balesdent, J.
    • Munoz, C.
    • Vidal, I.
    • Zagal, E.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world
  • Year: 2010
  • Summary: Sustainable agriculture should maintain soil organic carbon to prevent soil degradation and erosion, but soil C management still requires basic data on soil C dynamics under many climates, soil types and land uses. We applied a simple field method for the measurement of soil carbon dynamics, based on the natural 13C labelling technique of carbon inputs. The method implies the addition of locally produced maize material into the soil with C3 crops, in a simple, light and cost-effective design, and the kinetic analysis of soil 13C/ 12C. In Chile the approach was applied on a nine years fertility experiment with no till conditions sustaining a wheat-oat rotation, and followed thereafter for 5 years. The experimental site is located in the Andes pre-mountain (36degrees55′S, 71degrees53′O). The soil is of volcanic origin (medial, amorphic, mesic, Typic Haploxerands) and the crop rotation wheat-oat. The labeling technique showed that a very low amount (about 1 t ha -1) was incorporated to the soil (new C) during the time-period of the experiment (4 years). The ratio of remaining C/ added C after 4 years was very low (0.03) suggesting that the high carbon content of the soil can therefore be considered as due to a large amount of passive carbon, or to ancient carbon inputs, that have saturated the sorption capacity.
  • Authors:
    • Radicetti, E.
    • Mancinelli, R.
    • Campiglia, E.
    • Caporali, F.
  • Source: Crop Protection
  • Volume: 29
  • Issue: 4
  • Year: 2010
  • Summary: Cover crops and mulches are a suitable choice for sustainable agriculture because they improve weed control and crop performance. The aim of this research was to investigate weed control and nitrogen supply by using different winter cover crop species which were converted into mulches in spring. We carried out a 2-year field experiment where a tomato crop was transplanted into four different types of mulches coming from winter cover crops [(hairy vetch ( Vicia villosa Roth.), subclover ( Trifolium subterraneum L.), oat ( Avena sativa L.), and a mixture of hairy vetch/oat)] and in conventional treatment (tilled soil without mulch). The mixture of hairy vetch/oat cover crop produced the highest aboveground biomass (7.9 t ha -1 of DM), while the hairy vetch accumulated the highest N in the aboveground biomass (258 kg N ha -1). The oat cover crop was the most effective cover crop for suppressing weeds (on average -93% of weed aboveground biomass compared to other cover crops). After mowing the cover crop aboveground biomass was placed in strips as dead mulch into which the tomato was transplanted in paired rows. Weed density and total weed aboveground biomass were assessed at 15 and 30 days after tomato transplanting to evaluate the effect of mulches on weed control. All mulches suppressed weeds in density and aboveground biomass compared to the conventional system (on average -80% and -35%, respectively). The oat was the best mulch for weed control but also had a negative effect on the marketable tomato yield (-15% compared to the conventional treatment). Amaranthus retroflexus L. and Chenopodium album L. were typical weeds associated with the conventional treatment while a more heterogeneous weed composition was found in mulched tomato. Legume mulches, in particular hairy vetch, gave the best marketable tomato yield 28% higher than the conventional system both with and without nitrogen fertilization. This research shows that winter cover crops converted into dead mulch in spring could be used successfully in integrated weed management programs to reduce weed infestation in tomato crops.
  • Authors:
    • Amri, M.
    • Fernandez-Aparicio, M.
    • Kharrat, M.
    • Rubiales, D.
  • Source: Crop Protection
  • Volume: 29
  • Issue: 7
  • Year: 2010
  • Summary: Mycosphaerella pinodes is a serious pea disease of worldwide distribution. The increasing interest of sustainable tools for disease control, together with the lack of sufficient levels of genetic resistance has brought our interest in the use of intercropping as a tool for management of this disease. Effect of intercropping on M. pinodes severity was studied in field experiments performed in Spain and Tunisia, in which a susceptible pea cultivar was grown as monocrop and as two species mixed intercrop with either faba bean, barley, oat, triticale or wheat. Disease was significantly reduced in terms of both percent of diseased tissue per plant and vertical progress of lesions when pea was intercropped. Faba bean and triticale intercropped with pea showed the highest suppressive ability with above 60% of disease reduction. Oat, barley and wheat showed low to moderate M. pinodes suppressive effects. Suppressive effects can be ascribed to a combined reduction of host biomass, altered microclimate and physical barrier to spore dispersal.