Evaluation of fertigation applied to furrow and overhead irrigated cotton grown in a Black Vertosol in Southern Queensland, Australia

Field trials were conducted at gated pipe surface and overhead irrigation sites established to cotton (Gossypium hirsutum L.) to evaluate irrigation and fertigation management using a model-based control system. The control strategies determined the timing and volume of irrigation, and the rate of fertilizer-N to apply through fertigation. For this, nitrogen (N) was applied in-crop season using urea ammonium nitrate (UAN, 30% N solution) at a rate of 40 kg ha-1 N. At the furrows site, the uniformity of distribution of fertilizer-N applied through fertigation was satisfactory, which was achieved both at distance (600 m) and depth (0-600 mm). Applying fertilizer-N through fertigation, at the rate used in this study, showed relatively small (≤8%) improvements in cotton yield, which was explained by relatively high N rates (180 kg ha-1 N) applied before planting. Given current price ratios (fertilizer-to-cotton), application of N through fertigation appears to be economical in both systems, but relative agronomic efficiencies and economic return from the fertilizer applied were lower in furrow compared with overhead (P0.05). In both systems, fluxes were highest within five days of irrigation or fertigation, but they decreased significantly after that time as soil moisture content (water-filled pore space) and soil nitrate levels decreased due to crop uptake. Nitrous oxide fluxes were similar in furrow and overhead 15 days after the irrigation or fertigation event. Areas that warrant further investigation are presented and discussed, including the need for improved timing of fertilizer delivery during the irrigation cycle to ensure that N losses through leaching or gaseous evolution (e.g., N2O, N2) are not economically or environmentally significant

Spatial distribution of soil mechanical strength in a controlled traffic farming system as determined by cone index and geostatistical techniques

Controlled traffic farming (CTF) is a mechanisation system in which all load-bearing wheels are confined to the least possible area of permanent traffic lanes and where crops are grown in permanent, non-trafficked beds. In well-designed systems, the area affected by traffic represents less than 15% of the total field cropped area. The extent and distribution of soil compaction at locations laterally outboard of the permanent traffic lanes may explain the performance of the crop on the rows located either side of the wheeling. This compaction is due to lateral displacement of soil caused by repetitive wheeling, the effect of soil-tyre interaction and the soil conditions (strength) at the time of traffic. The impact of compaction on crop rows adjacent to permanent traffic lanes is also dependent on the seasonal effect of weather, because of changes in soil water availability. This work was conducted to model the spatial distribution of soil mechanical strength under increasing number of tractor passes to simulate the soil conditions that may be encountered in CTF systems at locations near-permanent traffic lanes. The study was conducted on a Typic Argiudoll (26% clay, 72% silt, 2% sand) with four traffic intensities (0, 6, 12 and 18 passes) using a 120 HP tractor (overall mass: 6.3 Mg). Traffic treatments were applied to experimental plots using a completely randomized block design with three replications per treatment. The spatial distribution of soil strength within wheeled and non-wheeled zones was determined using a cone penetrometer (depth range: 0–300 mm) and geostatistical techniques. In all treatments, cone index showed a quadratic response with depth, which explained between 67% and 88% of the variation in soil strength. The number of tractor passes had no effect on the range of spatial dependence of residuals. No differences were observed in the proportion of grid cells where penetration resistance was greater than 2 MPa (considered to be the soil strength limit for root growth of most arable crops) between-traffic treatments, or wheeled and non-wheeled zones, respectively. The overall mean proportion (± 95% confidence interval) of grid cells (4.9 ± 4.5%) suggested that this measure has a relatively high variability and therefore may not be a reliable parameter to be used in the design of future experimental work.Fil: Alesso, Carlos Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Agropecuarias del Litoral. Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral; ArgentinaFil: Cipriotti, Pablo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Masola, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Agropecuarias del Litoral. Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral; ArgentinaFil: Carrizo, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Agropecuarias del Litoral. Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral; ArgentinaFil: Imhoff, Silvia del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Agropecuarias del Litoral. Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral; ArgentinaFil: Rocha Meneses, L.. Estonian University of Life Sciences. Institute of Technology; EstoniaFil: Antille, D. L.. CSIRO Agriculture and Food; Australi

Quantifying the impacts of coal seam gas (CSG) activities on the soil resource of agricultural lands in Queensland, Australia

Coal seam gas (CSG) activities in the Surat and Bowen Basin areas of Queensland, Australia, cover approximately 300,000 km2 including regions of good quality agricultural lands. Without adequate knowledge of soil properties, hydrologic processes and control measures, the disturbed soil structure and landform in these regions are highly susceptible to soil degradation. The construction and installation of CSG infrastructures (e.g. roads, pipelines, hardstand and plant areas) cause various degrees of disturbance to the soil physical, chemical and biological characteristics. This disturbance may result in soil degradation through various forms including compaction, erosion processes, changes to organic carbon and soil nutrient store, exposure of potentially reactive/poor quality soils (e.g. acid sulphate soils, hyper-saline soils) or introduction of outside contaminants (poor quality water, weeds). Not only are soils directly disturbed by the footprint of the CSG operation but the surrounding soil landscape may be disturbed by secondary processes such as erosion and sedimentation. Soil compaction changes caused by CSG operations, including vehicle impacts and trench line installation, have been assessed by soil bulk density measurements. This measurement has been identified as a common impact by CSG operation and a key element of soil degradation of agricultural areas contributing poor vegetation establishment, tunnel and surface erosion processes and an ongoing decline for soil productivity. Quantifying the impacts of CSG activities on soils will inform the development of industry guidelines for impact minimisation and management of the soil resource on joint CSG-agricultural lands

Field evaluation of controlled traffic farming in central Europe using commercially available machinery

The progressive increase in the size and weight of farm machinery causes concerns due to the increased risk of soil compaction that arises from non-organized vehicle traffic. Controlled traffic farming (CTF) offers an effective means to manage compaction by confining all load-bearing wheels to the least possible area of permanent traffic lanes. Although CTF is relatively well-established in Australia and in some countries in Northern Europe, its benefits and suitability for Central European conditions have not been demonstrated. A long-term experimental site was established in 2010 in Nitra, Slovakia, using a 6 m 'OutTrac-CTF' system with shallow non-inversion tillage practices. The 16 ha experimental field of loam soil is representative of land used for arable cropping in Central Europe. Four traffic intensities (non-trafficked, one traffic event per year with a single pass, multiple passes with permanent traffic lanes, and random traffic) were evaluated using two traffic systems: controlled (CTF) and non-controlled traffic farming (referred to as random traffic farming or RTF). This article reports the findings derived from the first four years of the project and focuses on the effects of traffic systems on yields observed in cereal crops (winter wheat, spring barley, and maize) grown at the site in a rotation cycle. Significant differences (p < 0.1) in yield are reported due to the heterogeneity of the field and the seasonal effect of weather. The results of this investigation suggest that CTF systems have potential to increase production sustainably in arable farming systems in Central Europe. Well-designed CTF systems using commercially available machinery allow for reductions in the area affected by traffic of up to 50% compared with random, non-organized traffic systems. Results also show that in years when soil moisture was not limiting, the yield penalty from a single (annual) machine pass was relatively small (~5%). However, in dry years, compaction caused by multiple machinery passes may lead to yield losses of up to 33%. When considering the ratio of non-trafficked to trafficked area within the different CTF systems evaluated in this study, yield improvements of up to 0.5 t ha-1 for cereals are possible when converting from RTF to CTF. Given the assumptions made in the analyses, such yield increases translate into increased revenues of up to 117 USD ha-1 (1 Euro= 1.1 USD). For Central European farming systems, the main benefit of CTF appears to be improved efficiency and enhanced agronomic stability, especially in dry seasons, where the significant yield penalty from machinery passes is likely

The Spin Structure of the Nucleon

We present an overview of recent experimental and theoretical advances in our understanding of the spin structure of protons and neutrons.Comment: 84 pages, 29 figure

A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target

New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations.Comment: 40 pages, 28 figure

Measurement of the Collins and Sivers asymmetries on transversely polarised protons

The Collins and Sivers asymmetries for charged hadrons produced in deeply inelastic scattering on transversely polarised protons have been extracted from the data collected in 2007 with the CERN SPS muon beam tuned at 160 GeV/c. At large values of the Bjorken x variable non-zero Collins asymmetries are observed both for positive and negative hadrons while the Sivers asymmetry for positive hadrons is slightly positive over almost all the measured x range. These results nicely support the present theoretical interpretation of these asymmetries, in terms of leading-twist quark distribution and fragmentation functions.Comment: 9 Pages, 5 figure