• Authors:
    • Gaillard, B.
    • Foissy, D.
    • Dorvillez, D.
    • Carrouee, B.
    • Boucheny, P.
    • Biarnes, V.
    • Bedoussac, L.
    • Baranger, E.
    • Al-Rifai, M.
    • Naudin, C.
    • Corre-Hellou, G.
    • Makowski, D.
    • Bazot, M.
    • Pelzer, E.
    • Guichard, L.
    • Mansard, M.
    • Omon, B.
    • Prieur, L.
    • Yvergniaux, M.
    • Justes, E.
    • Jeuffroy, M.
  • Source: European Journal of Agronomy
  • Volume: 40
  • Year: 2012
  • Summary: Intensive agriculture ensures high yields but can cause serious environmental damages. The optimal use of soil and atmospheric sources of nitrogen in cereal-legume mixtures may allow farmers to maintain high production levels and good quality with low external N inputs, and could potentially decrease environmental impacts, particularly through a more efficient energy use. These potential advantages are presented in an overall assessment of cereal-legume systems, accounting for the agronomic, environmental, energetic, and economic performances. Based on a low-input experimental field network including 16 site-years, we found that yields of pea-wheat intercrops (about 4.5 Mg ha -1 whatever the amount of applied fertiliser) were higher than sole pea and close to conventionally managed wheat yields (5.4 Mg ha -1 on average), the intercrop requiring less than half of the nitrogen fertiliser per ton of grain compared to the sole wheat. The land equivalent ratio and a statistical analysis based on the Price's equation showed that the crop mixture was more efficient than sole crops particularly under unfertilised situations. The estimated amount of energy consumed per ton of harvested grains was two to three times higher with conventionally managed wheat than with pea-wheat mixtures (fertilised or not). The intercrops allowed (i) maintaining wheat grain protein concentration and gross margin compared to wheat sole crop and (ii) increased the contribution of N 2 fixation to total N accumulation of pea crop in the mixture compared to pea sole crop. They also led to a reduction of (i) pesticide use compared to sole crops and (ii) soil mineral nitrogen after harvest compared to pea sole crop. Our results demonstrate that pea-wheat intercropping is a promising way to produce cereal grains in an efficient, economically sustainable and environmentally friendly way.
  • Authors:
    • Baraibar, B.
    • Torra, J.
    • Atanackovic, V.
    • Westerman, P.
  • Source: IOBC/WPRS Bulletin
  • Volume: 75
  • Year: 2012
  • Summary: In dryland cereals in NE Spain, the harvester ant, Messor barbarus L., is responsible for a high percentage of seed removal. A direct density dependent response of seed predators to seed patches may help regulate weed populations. In this study, we investigated if seed removal rate by harvester ants is influenced by weed seed density. For this reason, 60 circular areas of 1 m 2 were created inside four 50*50 m blocks after cereal harvest Lolium multiflorum L. seeds were applied at 1000, 2000, 5000, 10000 or 20000 seeds/m 2, in ten randomly selected areas each; the remaining 10 were used to test the methodology used to retrieve the seeds. After 24h, the remaining seeds were collected using vacuum cleaners or a D-vac and seed removal rates were estimated. In three of the four blocks, seed removal was extremely high (99-100%), and the response was therefore density independent Here, nests densities ranged from 468 to 900 nests/ha. In the fourth block seed removal was 91%, and here nest density was lower (284 nests/ha).
  • Authors:
    • Weatherhead, E.
    • Jones, R.
    • Keay, C.
    • Daccache, A.
    • Stalham, M.
    • Knox, J.
  • Source: Journal of Agricultural Science
  • Volume: 150
  • Issue: 2
  • Year: 2012
  • Summary: The viability of commercial potato production is influenced by spatial and temporal variability in soils and agroclimate, and the availability of water resources where supplementary irrigation is required. Soil characteristics and agroclimatic conditions greatly influence the cultivar choice, agronomic husbandry practices and the economics of production. Using the latest (UKCP09) scenarios of climate change for the UK, the present paper describes a methodology using pedo-climatic functions and a geographical information system (GIS) to model and map current and future land suitability for potato production in England and Wales. The outputs identify regions where rainfed production is likely to become limiting and where future irrigated production would be constrained due to shortages in water availability. The results suggest that by the 2050 s, the area of land that is currently well or moderately suited for rainfed production would decline by 88 and 74%, respectively, under the 'most likely' climate projections for the low emissions scenario and by 95 and 86%, respectively, for the high emissions scenario, owing to increased likelihood of dry conditions. In many areas, rainfed production would become increasingly risky. However, with supplementary irrigation, c. 0.85 of the total arable land in central and eastern England would remain suitable for production, although most of this is in catchments where water resources are already over-licensed and/or over-abstracted; the expansion of irrigated cropping is thus likely to be constrained by water availability. The increase in the volume of water required due to the switch from rainfed- to irrigated-potato cropping is likely to be much greater than the incremental increase in water demand solely on irrigated potatoes. The implications of climate change on the potato industry, the adaptation options and responses available, and the uncertainty associated with the land suitability projections, are discussed.
  • Authors:
    • Finlay, L. A.
    • Weaver, T. B.
    • Hulugalle, N. R.
    • Lonergan, P.
  • Source: Soil Research
  • Volume: 50
  • Issue: 4
  • Year: 2012
  • Summary: Comparative studies of soil quality and energy use in two- and three-crop rotations in irrigated cotton ( Gossypium hirsutum L.) based cropping systems under varying stubble management practices in Australian Vertosols are sparse. Our primary objective was to quantify selected soil quality indices (salinity, sodicity, exchangeable cations, nitrate-N, pH), crop yields, and greenhouse gas emissions in four irrigated cotton-based cropping systems sown on permanent beds in a Vertosol with subsoil sodicity near Narrabri in north-western New South Wales. A secondary objective was to evaluate the efficacy of sowing vetch in rotation with cotton over a long period on the incidence of black root-rot in cotton seedlings. Results: presented in this report pertain to the period June 2005-May 2011. The experimental treatments were: cotton-cotton; cotton-vetch ( Vicia benghalensis L.); cotton-wheat ( Triticum aestivum L.), where wheat stubble was incorporated; and cotton-wheat-vetch, where wheat stubble was retained as in-situ mulch. Vetch was terminated during or just before flowering by a combination of mowing and contact herbicides, and the residues were retained as in-situ mulch. Soil pH, electrical conductivity (EC 1:5), Cl -, NO 3--N, exchangeable cations, exchangeable sodium percentage (ESP), electrochemical stability index (=EC 1:5/ESP), and EC 1:5/ESC (exchangeable sodium concentration) were evaluated in samples taken from the 0-1.2 m depth before sowing cotton during late September or early October of each year. Incidence of black root-rot was assessed 6 weeks after sowing cotton. Compared with sowing cotton every year, including wheat in cotton-based cropping systems improved cotton yield and reduced soil quality decline, emissions of carbon dioxide equivalents (CO 2-e) per unit area, and CO 2-e emissions per unit of cotton yield. Including vetch in the rotation was of negligible benefit in terms of yield and CO2-e emissions per unit of yield. The rate of soil quality decline was unaffected by including vetch in a cotton-wheat rotation but was accelerated when included in a cotton-cotton sequence. Among all cropping systems, soil quality was best with cotton-wheat and cotton-wheat-vetch but poorest with cotton-vetch. Although CO2-e emissions associated with growing 1ha of cotton could be reduced by 9% by growing vetch because of substituting fixed atmospheric N for N fertiliser derived from fossil fuels, this advantage was partly negated by the emissions from farming operations associated with growing a vetch crop. Relative to a two-crop rotation (one cotton-one rotation crop), negligible benefits in terms of yield, soil quality, greenhouse gas emissions, and black root-rot control accrued from a three-crop rotation (one cotton-two rotation crops). Incidence of black root-rot increased as the number of cotton crops sown increased. In addition to the cropping systems, soil quality indices and yield were significantly influenced by irrigation water quality and climate.
  • Authors:
    • Sil, A. C. da
    • Azevedo, F. A. de
    • Correa, F. E.
    • Kupper, K. C.
  • Source: Scientia Horticulturae
  • Volume: 134
  • Year: 2012
  • Summary: The objective of this research was to study the viability of Bacillus subtilis (ACB-69) to control the casual agent in postbloom fruit drop, Colletotrichum acutatum under field conditions. During the 2007/2008 crop season, B. subtilis was tested in 5% (5*10 8 cfu ml -1) and 10% (1*10 9 cfu ml -1) concentrations on 'Pera' sweet orange ( Citrus sinensis (L.) Osbeck) plants grafted on Rangpur lime ( Citrus limonia Osb.), in Botucatu, Sao Paulo, Brazil. The same treatments were repeated in the 2008/2009 crop season with and without adding a carbon source (molasses 5%) to 'Valencia' sweet orange plants grafted on Rangpur lime. Additional experiment was conducted to determine the most appropriate flower growth stage to apply the biocontrol agent. The biological products were applied with an air assisted sprayer in all experiments with the intention of evaluating the practicality of this type of sprayer. A weekly application of B. subtilis (5*10 8 cfu ml -1) reduced the quantity of symptomatic flowers by 47% while the chemical treatment only had an 18% reduction. On the other hand, B. subtilis (10% or 1*10 9 cfu ml -1) applied weekly or applied one week before to the "green bud bloom" stage (like a preventive control) provided a greater average number of effective fruits (ANEF). The addition of a carbon source at the time of application, did not favor the antagonistic activity of bacteria. In controlling postbloom fruit drop, the best time to apply B. subtilis was observed in the open flower stage when the percentage of symptomatic flowers was evaluated. However, when the bacterium was applied in all flowering stages there was a greater average number of effective fruits. The use of air assisted sprayer helped implement the antagonistic on a commercial scale.
  • Authors:
    • Mezencev, N.
    • Collet, J. M.
    • Monot, C.
  • Source: Acta Horticulturae
  • Issue: 942
  • Year: 2012
  • Summary: The development of a model for the prediction of the risk appearance of downy mildew on Artichoke ( Bremia lactucae) was based on a biological model close to the Guntz and Divoux's one established on potatoes. The model uses simple meteorological data (relative humidity of air, hourly temperatures and rainfalls) and includes user's data (treatments, irrigation, stage of the crop and variety). The first year of the model fittings showed a good visualization of the real epidemic. Laboratory tests refine our knowledge about the life cycle and, associated to field observations, will allow to quantify more precisely the models parameters.
  • Authors:
    • Djigal, D.
    • Saj, S.
    • Rabary, B.
    • Blanchart, E.
    • Villenave, C.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Conservation agriculture (CA) is rapidly developing in Madagascar but little is known about its effects on local soil functioning. To assess some of those effects, we investigated the effects of three CA systems and two levels of fertilization on soil functioning using nematofauna as indicator. The systems consisted in (i) soybean (Glycine max L.)-maize (Zea mays L) rotation with mulch of residues, CA-R; (ii) bean (Phaseolus vulgaris L.)-soybean rotation with living mulch of Pennisetum clandestinum, CA-K; (iii) continuous maize with living mulch of Desmodium uncinatum, CA-D and were compared with soybean-maize under conventional tillage (CT) and natural fallow (NF). The fertilization levels consisted in ( i) farmyard manure, FYM; and (ii) farmyard manure + mineral fertilizers, FYM + NPK. Located in the Highlands of Madagascar, the experiment was setup in 1991 and andic Dystrustept soil had been sampled in 2005-2007. We measured nematode abundances and ecological indices as well as the abundance and biomass of soil macrofauna, soil water and organic C and N contents and plant yields. We hypothesized that (1) CA including maize in monoculture would lead to higher abundance of plant-parasitic nematodes; (2) both dead-residue mulch and inorganic fertilization would lead to a more basal nematode community structure; and (3) that the combination of system effects on soil nematode community would be able to forecast differential crop yields for the CA systems. Our results show that CA systems tested were able to support better/comparable maize and soybean yields compared with CT, provided that crop rotation is correctly managed. Supporting our first hypothesis, abundance of plant parasitic nematodes was (40-150 times) higher under maize monoculture. Abundance of soil nematofauna and trophic groups (excepted carnivores and omnivores) was stable during the three years. Inorganic fertilization increases carnivorous and omnivorous nematodes to 122% and 140%, respectively. Ecological indices showed that soil functioning of CA systems was intermediate between that NF and CT. CA systems were characterized by a highly structured soil food-web compared with CT. Yet, soil processes intensity revealed to be lower in CA with dead mulch compared with CA with living mulch, contrasting with our second hypothesis. The characterization of nematofauna discriminated well the different systems and supports our third hypothesis. Nematode structure and enrichment indices were significantly correlated to soil organic C and N content as well as grain yields. They proved to be powerful bio-indicators of soil functioning in the CA systems studied.
  • Authors:
    • Gruber, S.
    • Pekrun, C.
    • Möhring, J.
    • Claupein, W.
  • Source: Soil & Tillage Research
  • Volume: 121
  • Year: 2012
  • Summary: The study provides information to more reliably estimate the value of conservation tillage in a temperate climate. Tillage effects on yield and weeds were evaluated in field experiments at two sites in SW Germany between 1999 and 2010. Tillage varied at site Ihinger Hof from mouldboard plough (P), chisel plough (CP), rototiller (RTT), varying P and CP (VAR), to no tillage (NT), partially combined with stubble tillage (S). Tillage at site Meiereihof was S/P, S/CP, and NT. Crop rotations included winter wheat (WW, Triticum aestivum), triticale (TR, Triticosecale), oat (OA, Avena sativa), silage maize (SM, Zea mays) and oilseed rape (OSR, Brassica napus) at Ihinger Hof, and winter wheat, spring barley (SB, Hordeum vulgare), silage maize, sugar beets (SBE. Beta vulgaris) and faba bean (FB, Vicia faba) at Meiereihof. At Ihinger Hof, tillage had an effect on yield (P > F = 0.0049), but no effects were found on crop emergence and crop density. Tillage effects on yield were consistent across crops though differences between crops appeared to exist. The yield of S/P, the standard tillage, was 8.5 (WW), 7.7 (TR), 4.7 (OA), 18.3 (SM) and 4.1 (OSR) t DM ha(-1) at Ihinger Hof, with yield under NT always significantly lower than S/P by 7.3% on average for all crops. At Meiereihof, yields ranged from 7.2 to 8.0 (WW), 3.3 to 4.2 (SB), 19.8 to 21.5 (SM) and 3.1 to 3.2 (FB) t DM ha(-1), and 61.3 to 67.6 FM ha(-1) for SBE. Yield was reduced by 4.5% from S/P to S/CP (P > F = 0.0516), and by about 10% from S/P to NT (P > F = 0.0009). Weed density ranged between 0.5 and 44 plants m(-2) at Ihinger Hof and was higher in treatments without stubble tillage and under non-inversion tillage, though significance differed for the different classes of weeds. NT led to weed infestation about 2-20 times higher than S/P. The interaction crop x treatment indicated that factors other than tillage influenced weed infestation. It is unlikely that weed infestation and reduced yield will be problems in temperate climates if soil disturbance through tillage is reduced. Non-inversion tillage can easily replace inversion tillage, and stubble tillage can be added to primary tillage if needed to reduce weeds. Since no specific tillage method was unequivocally superior to another one, any method well suited to specific regional and farm conditions can be adopted successfully.
  • Authors:
    • Conesa, M. R.
    • Domingo, R.
    • Perez-Pastor, A.
    • Pagan, E.
    • Caro, M.
  • Source: Agricultural Water Management
  • Volume: 111
  • Year: 2012
  • Summary: A two year experiment on Fortune mandarin trees (Clementina * mandarina Dancy ( Citrus clementina Hort. Ex. Tanaka * Citrus reticulata Blanco)) grafted onto Cleopatra mandarin ( Citrus reshni Hort. ex. Tanaka) rootstock was carried out with the aim of studying the suitability of midday stem water potential (psi stem) and trunk diameter reference baselines for irrigation scheduling. Plants were drip-irrigated with saline water during the second year (EC 25°C ~ 4 dS m -1). Measurements of psi stem, trunk daily growth rate (TGR) and maximum daily trunk shrinkage (MDS) were related with meteorological variables. Among them, MDS presented the best behavior. The mean temperature during the period 10.00-15.00 h solar time ( Tmd) was the environmental variable that best correlated with MDS, although there were no differences with other T-related variables (daily mean and daily maximum values). MDS data from stage III did not correlate with meteorological variables and fit-linear regressions became better with data from stages I and II (March-October), this being the period which covers 80% of total crop water requirements. Despite the different conditions that the trees were submitted to during the experimental period, i.e. irrigation water with different salinity and crop load, inter-annual differences were not observed in the reference baselines obtained.
  • Authors:
    • Amanullah, M. M.
    • Rajendran, K.
    • Vaiyapuri, K.
  • Source: Madras Agricultural Journal
  • Volume: 99
  • Issue: 1/3
  • Year: 2012
  • Summary: Field experiments were conducted during winter 2006-07 and 2007-08 at Tamil Nadu Agricultural University, Coimbatore to find out the effect of drip irrigation on the productivity and water use efficiency in Bt-cotton ( Gossypium hirsutum L.). The experiments were laid out in a randomized block design replicated four times. The treatments consisted of drip irrigation at 0.40, 0.60, 0.80 and 1.0 ET c (Crop evapotranspiration) compared with farmers' method (flood irrigation method). The results revealed that application of water to Bt-cotton through drip resulted in better growth, higher seed cotton yield and better quality of lint than the surface method. The yield advantage due to different irrigation schedules through drip based on ETc was 26.2 and 12.8% over surface method during 2006-07 and 2007-08, respectively. Among the irrigation through drip, irrigation at 0.80 ET c recorded better growth and gave higher seed cotton yield than irrigation at 0.60 ET c. The water use efficiency with drip irrigated Bt-cotton was 44.4% higher than the flood method of irrigation.