• Authors:
    • Hodgson, J.
    • Bogaard, A.
    • Charles, M.
    • Jones, G.
  • Source: Journal of Archaeological Science
  • Volume: 37
  • Issue: 1
  • Year: 2010
  • Summary: This paper brings together the results of five present-day studies of arable weed ecology, and applies these to the identification of past crop husbandry regimes on the basis of archaeobotanical weed assemblages. The contrasting husbandry regimes covered by the present-day studies include irrigation and dry farming, fallowing and rotation, intensive and extensive cultivation, and autumn and spring sowing. The weed floras associated with these regimes were analysed in terms of the functional ecology of the species represented. These same functional attributes, that distinguished contrasting regimes, were then measured for the weed species found accompanying crop seeds in two archaeobotanical studies, of the Islamic site of Khirbet Faris, S. Jordan and Neolithic sites in central Europe. Analyses using these functional measurements resulted in the identification of irrigation at the former and in the identification of sowing time and intensive cultivation at the latter.
  • Authors:
    • Ginovart, M.
    • Josa, R.
    • Sole, A.
  • Source: International Agrophysics
  • Volume: 24
  • Issue: 2
  • Year: 2010
  • Summary: In an experiment conducted in NE Spain, cereals and legumes were rotated for seven cycles using two different tillage techniques - conventional tillage and direct drilling (no-tillage: NT). Straw was removed after harvesting in both tillage systems. With NT, more than 30% of the soil surface was still covered by residues (stubble) at sowing. The soil was Calcic Cambisol and the climate aridity index was 0.76. The climatic water balance was negative, at -187 mm y(-1) from 1950 to 1980. The aims of the study were to determine the effect of tillage system on 2-D macroporosity by micromorphology, and bulk density (excavation method) of the upper layer of the ploughed horizon. To identify differences, either parametric or nonparametric statistical tests were performed depending on sample size. Direct drilling with residue removal affected bulk density, macroporosity and mean macropore area in the top 10 cm of the profile. The same effects were observed under conventional tillage. The upper layer of the studied horizon had higher total porosity than the layer beneath with both treatments. The upper layer of the horizon showed unfavourable physical conditions with direct drilling.
  • Authors:
    • Meijide, A.
    • Sanz-Cobena, A.
    • Sanchez-Martin, L.
    • Quemada, M.
    • Vallejo, A.
  • Source: European Journal of Soil Science
  • Volume: 61
  • Issue: 5
  • Year: 2010
  • Summary: The aim of this study was to evaluate the pattern of nitrous oxide (N 2O) and methane (CH 4) fluxes, and leaching losses of nitrate (NO 3-) and dissolved organic C (DOC), during a fallow-onion crop-fallow cycle in a Mediterranean area. The importance of the fallow (intercrop) period and the type of fertilizer were also evaluated. Goat and chicken manure (M) from an organic farm, digested pig slurry (DPS) and urea (U) were applied at a rate of 110 kg N ha -1 and compared with a zero N treatment (Control). The crop period contributed more than each fallow period to the total N 2O emission (ranging from 70 to 85% of the total emission, depending on the treatment). The variability of rainfall during fallow periods affected N 2O emissions, with the highest fluxes observed in the second fallow, which was the wetter. Negative net fluxes of N 2O (0 to -0.4 mg N 2O-N m -2 day -1) were mainly observed during the irrigation period and in fallow periods. The type of fertilizer had no effect on N 2O fluxes, but influenced the CH 4 oxidation. The largest CH 4 emission was from the manure treatment (2.4 mg CH 4-C m -2 day -1) during the irrigation period. The lowest NO 3- but highest DOC leaching rates were measured during the second fallow period from the manure treated plots (0.2 kg NO 3--N ha -1 and 3.9 kg C ha -1), which also had the highest drainage. The use of OM, therefore, seems to be a suitable method to reduce the environmental impacts associated with N leaching as well as increase the potential to denitrify NO 3- in groundwater.
  • Authors:
    • Vanderlinden, K.
    • Murillo, J. M.
    • Madejon, E.
    • Lopez-Garrido, R.
    • Melero, S.
    • Ordonez, R.
    • Moreno, F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 133
  • Issue: 1-2
  • Year: 2009
  • Summary: Long-term field experiments can provide relevant information regarding soil organic carbon sequestration under different soil tillage systems. Especially, conservation tillage (CT) has been proved to be a practice that highly contributes to improve soil quality. For that reason, the study of soil quality indicators, such as organic fractions, are useful tools to assess changes caused by different soil tillage systems in long-term field experiments. We evaluated long-term effects of conservation tillage on soil carbon fractions and biological properties in a sandy clay loam Entisol (soil A) and in a clay Vertisol (soil B) located in semi-arid SW Spain. Cereal-sunflower-legume rotations under rainfed conditions were used in both soils in which conservation tillage (CT) was compared to traditional tillage (TT). Soil samples were collected at three depths (0-5, 5-10 and 10-20 cm) four months after sowing a pea crop ( Pisum arvense L.) in the Entisol and a wheat crop ( Triticum aestivum L.) in the Vertisol. Labile fractions of the total organic carbon (TOC) were determined as active carbon (AC) and water soluble carbon (WSC). Biological status was evaluated using soil microbial biomass carbon (MBC) and enzymatic activities [dehydrogenase activity (DHA), o-diphenol oxidase activity (Dphox), and beta-glucosidase activity (beta-glu)]. As a rule, the contents of AC, WSC, MBC, beta-glu and Dphox in soil A and contents of TOC, AC and DHA in soil B were higher in CT than in TT, at the 0-5 cm depth. In both soils, the studied parameters decreased with depth under both tillage treatments (TT and CT). Values of AC, TOC, MBC and beta-glu were positively correlated with each other ( p
  • Authors:
    • Ruiz, J. C.
    • Vanderlinden, K.
    • Melero, S.
    • Madejon, E.
  • Source: The Journal of Agricultural Science
  • Volume: 147
  • Issue: 1
  • Year: 2009
  • Summary: Soil enzyme activities are widely utilized as rapid and sensitive indicators in discriminating among soil management effects. The objective of the present study was to compare the influence of conservation tillage, i.e. direct drilling (DD) (residue cover is left on the soil surface) v. conventional tillage (CT), on soil chemical and biochemical properties in a crop rotation (cereals-sunflower-legumes) under dryland production in a semi-arid Mediterranean Vertisol after 23 years. A randomized experimental design was established. Soil biological status was evaluated by measuring of enzymatic activities (dehydrogenase, beta-glucosidase, alkaline phosphatase and protease). Total organic carbon (TOC) contents were greater in soils managed by DD than those found by CT. Except for protease activity, enzymatic activity values were approximately 2-fold higher in soils under DD than in soils under CT. The beta-glucosidase, alkaline phosphatase and dehydrogenase values showed a high correlation (from r=0.481 to r=0.886, P≤0.01) with TOC contents and they were correlated with each other (from r=0.664 to r=0.923, P≤0.01). The coefficient of variation of biochemical properties was higher than those of chemical properties in both treatments. Principal component analysis (PCA) showed that two principal components explained 58% and 20% of the total variability. The first principal component was influenced mostly by beta-glucosidase, dehydrogenase and TOC, whereas the second was influenced by pH. The first component effectively differentiated managed soil under both agriculture practices. In general, long-term soil conservation management by DD in a dryland farming system improved the quality of this Vertisol by enhancing its organic matter content and biochemical activity.
  • Authors:
    • Baraibar, B.
    • Westerman, P. R.
    • Recasens, J.
  • Source: Journal of Applied Ecology
  • Volume: 46
  • Issue: 2
  • Year: 2009
  • Summary: Agricultural intensification can cause a huge increase in productivity. However, associated costs in terms of reduced, self-regulation and increased reliance on external inputs for the control of pests, diseases and weeds are seldom taken into account or acknowledged. A pro-active approach in which ecosystems services are documented and potential effects of changes in agricultural practices evaluated may lead to more informed decisions prior to implementation. We investigated the effects of management of cereal production in a semi-arid region on weed seed mortality caused by predators. Seed losses have a greater impact on weed population size than any other life cycle process and should therefore be of significance for natural weed control. We hypothesized that the conversion from rain-fed to irrigated production should lead to reduced and the adoption of no-till techniques to increased seed predation. Seed removal and seed predator populations were monitored in irrigated (N = 3) and rain-fed cereal fields (N = 6) and field margins. Of the dryland fields half was conventionally tilled and the other half no-till. Seed removal (g g(-1) 2-days(-1)) was followed from April 2007 until June 2008, using Petri-dishes and exclosure cages. Populations of harvester ants were estimated by direct nest counts; rodent populations by Sherman live traps. Seed removal in dryland cereals, mainly by harvester ants Messor barbarus was high from mid April to mid October, and should cause a strong weed suppressive effect. Seed removal in irrigated cereals, mainly by granivorous rodents Mus spretus, was low. Seed removal was higher in no-till than in conventional fields and corresponded to differences in harvester ant nest densities. Synthesis and applications. Our results show that tillage and irrigation in a semi-arid cereal production system results in a reduction and total annihilation of granivorous harvester ants, respectively. The concurrent decline in weed seed mortality could lead to increased herbicide use and dependency. In particular, in areas where economic margins are small or the environmental costs of tillage and irrigation high, the increased costs of chemical weed control may exceed the benefits. Here, preserving biodiversity to enhance natural weed control is a viable alternative to agricultural intensification.
  • Authors:
    • Moreno, F.
    • Murillo, J. M.
    • López-Garrido, R.
    • Melero, S.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 2
  • Year: 2009
  • Summary: Short- and long-term field experiments are necessary to provide important information about how soil carbon sequestration is affected by soil tillage system; such systems can also be useful for developing sustainable crop production systems. In this study, we evaluated the short- and long-term effects of conservation tillage (CT) on soil organic carbon fractions and biological properties in a sandy clay loam soil. Both trials consisted of rainfed crop rotation systems (cereal-sunflower-legumes) located in semi-arid SW Spain. In both trials, results were compared to those obtained using traditional tillage (TT). Soil samples were taken in flowering and after harvesting of a pea crop and collected at three depths (0-5, 5-10 and 10-20 cm). The soil organic carbon fractions were measured by the determination of total organic carbon (TOC), active carbon (AC) and water soluble carbon (WSC). Biological status was evaluated by the measurement of soil microbial biomass carbon (MBC) and enzymatic activities [dehydrogenase activity (DHA), o-diphenol oxidase activity (DphOx), and beta-glucosidase activity (beta-glu)]. The contents of AC and MBC in the long-term trial and contents of AC in the short-term trial were higher for CT than TT at 0-5 cm depth for both sampling periods. Furthermore, DHA and beta-glucosidase values in the July sampling were higher in the topsoil under conservation management in both trials (short- and long-term). The parameters studied tended to decrease as depth increased for both tillage system (TT and CT) and in both trials with the exception of the DphOx values, which tended to be higher at deeper layers. Values of DHA and beta-glu presented high correlation coefficients (r from 0.338 to 0.751, p <= 0.01) with AC, WSC and TOC values in the long-term trial. However, there was no correlation between either TOC or MBC and the other parameters in the short-term trial. In general, only stratification ratios of AC were higher in CT than in TT in both trials. The results of this study showed that AC content was the most sensitive and reliable indicator for assessing the impact of different soil management on soil quality in the two experiments (short- and long-term). Conservation management in dryland farming systems improved the quality of soil under our conditions, especially at the surface layers, by enhancing its storage of organic matter and its biological properties, mainly to long-term. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Zaragoza, C.
    • Aibar, J.
    • Cavero, J.
    • Pardo, G.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 84
  • Issue: 3
  • Year: 2009
  • Summary: Under semiarid conditions the response of crops to synthetic fertilizers is often reduced. Organic fertilizers can be used to provide a continuous source of nutrients for the crops. The soil nitrogen and crop yield in a rotation of durum wheat ( Triticum durum)-fallow-barley ( Hordeum vulgare)-vetch ( Vicia sativa) were studied during 4 years when synthetic fertilizer (chemical), compost (organic) or no fertilizer (control) were applied in a field with high initial contents of soil NO 3-N (>400 kg N ha -1), phosphorus (22 mg kg -1) and potassium (>300 mg kg -1). Changes in soil organic matter, phosphorus and potassium were also measured. During the crop period, chemical fertilization significantly increased the content of soil NO 3-N in the first 0.30 m of soil with respect to organic fertilization and the control. The yield of wheat and barley was not increased after applying chemical or organic fertilizer with respect to the unfertilized plots. The estimated losses of nitrogen were similar for the three types of fertilization, as well as the uptake of nitrogen for the total biomass produced. The initial levels of organic matter and phosphorus were maintained, even in the plots that were not fertilized, while the potassium decreased slightly. Thus, the rotation and burying of crop residues were enough to maintain the crop yield and the initial content of nutrients.
  • Authors:
    • Pérez, R.
    • Ayuso, J. L.
    • Taguas, E. V.
    • Yuan, Y.
    • Peña, A.
  • Source: Earth Surface Processes and Landforms
  • Volume: 34
  • Issue: 5
  • Year: 2009
  • Summary: Despite the high risk of erosion in olive Orchards located in mountainous areas in Spain, little research has been carried out to account for the complexity and interaction of the natural processes of runoff and soil erosion on the catchment scale or small catchment scale. In this Study, a microcatchment of 6.7 ha in a mountainous area under no-tillage farming with hare soil was Set Up to record runoff and sediment. Soil erosion and runoff patterns were monitored Over a two-year period. Totally events were observed. The data were analysed, and then Used to calibrate the, AnnAGNPS model, which allowed Lis to complete the data period and describe the hydrological and erosive behaviour on a monthly and annual basis. A high variability in catchment responses was observed, due to differences in the storms and to the effect of the surface Soil moisture content. Maximum intensities of 10 and 30 min determined the final runoff Values while the total sediment leads were dependent on the rainfall depth. The impact of management on the reduction of porosity can explain the relationship between runoff and intensity in the microcatchment. However, the impact of the spatial scale meant that the transport of sediment required substantial rainfall depths to ensure a Continuous flew front the hillslopes. The results of the calibration (E > 0.60 and r > 0.75) on the event and monthly scale confirmed the applicability of AnnAGNPS to predict runoff and erosion in the microcatchment. The predicted average runoff coefficient was 3.3% for the study period and the total average Sediment loads, 1.3 Mg/ha/yr. Despite these low Values, the model Simulation Showed that much larger runoff coefficients and soil losses can be expected for periods with several consecutive years in which the annual rainfall depth was over 500 mm). The use of cover is recommended to prevent the high levels of erosion associated with these conditions. Copyright (C) 2009 John Wiley & Sons, Ltd,
  • Authors:
    • Durán Zuazo, V. H.
    • Rodríguez Pleguezuelo, C. R.
    • Arroyo Panadero, L.
    • Martínez Raya, A.
    • Francia Martínez, J. R.
    • Cárceles Rodríguez, B.
  • Source: Pedosphere
  • Volume: 19
  • Issue: 4
  • Year: 2009
  • Summary: Sloping and mountainous olive production systems are widespread, occupying large parts of the Mediterranean landscape prone to water erosion. Soil erosion, runoff, and soil water content patterns over a three-year period were monitored in erosion plots on a mountainside with rainfed olive (Olea europaea cv. Picual) trees under: 1) non-tillage with barley strips of 4 m width (BS); 2) non-tillage with native vegetation strips of 4 m width (NVS); and 3) non-tillage without plant strips (NT). The erosion plots, located in Lanjaron (Granada, south-eastern Spain), on a 30% slope, were 192 m(2) in area. For assessing soil water dynamics in real-time and near-continuous soil water content measurements, multisensor capacitance probes were installed in the middle of plant strips and beneath the olive tree at five soil depths (10, 20, 30, 50, and 100 cm). The highest erosion and runoff rates were measured under NT, with a mean of 17.3 Mg ha(-1) year(-1) and 140.0 mm year(-1), respectively, over the entire study period. The BS and NVS with respect to the NT reduced erosion by 71% and 59% and runoff by 95% and 94%, respectively. In general, greater available soil water content was found under BS than NVS and NT, especially beneath the olive tree canopies. These results supported the recommendation of non-tillage with barley strips in order to reduce erosion and to preserve soil water for trees in traditional mountainous olive-producing areas, where orchards cover vast tracts of land.