• Authors:
    • Dalal, R. C.
    • Page, K. L.
    • Pringle, M. J.
    • Allen, D. E.
  • Source: The Rangeland Journal
  • Volume: 32
  • Issue: 2
  • Year: 2010
  • Summary: The accurate measurement of the soil organic carbon (SOC) stock in Australian grazing lands is important due to the major role that SOC plays in soil productivity and the potential influence of soil C cycling on Australia's greenhouse gas emissions. However, the current sampling methodologies for SOC stock are varied and potentially conflicting. It was the objective of this paper to review the nature of, and reasons for, SOC variability; the sampling methodologies commonly used; and to identify knowledge gaps for SOC measurement in grazing lands. Soil C consists of a range of biological materials, in various SOC pools such as dissolved organic C, micro- and meso-fauna (microbial biomass), fungal hyphae and fresh plant residues in or on the soil (particulate organic C, light-fraction C), the products of decomposition (humus, slow pool C) and complexed organic C, and char and phytoliths (inert, passive or resistant C); and soil inorganic C (carbonates and bicarbonates). Microbial biomass and particulate or light-fraction organic C are most sensitive to management or land-use change; resistant organic C and soil carbonates are least sensitive. The SOC present at any location is influenced by a series of complex interactions between plant growth, climate, soil type or parent material, topography and site management. Because of this, SOC stock and SOC pools are highly variable on both spatial and temporal scales. This creates a challenge for efficient sampling. Sampling methods are predominantly based on design-based (classical) statistical techniques, crucial to which is a randomised sampling pattern that negates bias. Alternatively a model-based (geostatistical) analysis can be used, which does not require randomisation. Each approach is equally valid to characterise SOC in the rangelands. However, given that SOC reporting in the rangelands will almost certainly rely on average values for some aggregated scale (such as a paddock or property), we contend that the design-based approach might be preferred. We also challenge soil surveyors and their sponsors to realise that: (i) paired sites are the most efficient way of detecting a temporal change in SOC stock, but destructive sampling and cumulative measurement errors decrease our ability to detect change; (ii) due to (i), an efficient sampling scheme to estimate baseline status is not likely to be an efficient sampling scheme to estimate temporal change; (iii) samples should be collected as widely as possible within the area of interest; (iv) replicate of laboratory analyses is a critical step in being able to characterise temporal change. Sampling requirements for SOC stock in Australian grazing lands are yet to be explicitly quantified and an examination of a range of these ecosystems is required in order to assess the sampling densities and techniques necessary to detect specified changes in SOC stock and SOC pools. An examination of techniques that can help reduce sampling requirements (such as measurement of the SOC fractions that are most sensitive to management changes and/or measurement at specific times of the year, preferably before rapid plant growth, to decrease temporal variability), and new technologies for in situ SOC measurement is also required.
  • Authors:
    • Sommer, R.
    • Ryan, J.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Division Symposium 3.2 Nutrient best management practices
  • Year: 2010
  • Summary: While globally fertilizers have had a major impact on food production for the past half-century, the general use of chemical fertilizers in the semi-arid areas of the world is a more recent development. This is particularly true of the Mediterranean region, especially in North Africa and West Asia. Traditionally, the cropping system involved growing cereals (barley and wheat) in rotation with fallow to conserve moisture; sheep and goats were an integral part of the low-input system. Drought was a constant constraint on crop yields. In the past few decades, significant developments have occurred to increase agricultural output; new high-yielding disease resistant varieties; mechanization; irrigation; pest control; and particularly the use of chemical fertilizers as a supplement to the limited animal manures available. Research at the International Center for Agricultural Research in the Dry Areas (ICARDA) in collaboration with the national agricultural systems in the mandate countries of the region has made significant strides in fertilizer research. While much has been achieved in terms of best fertilizer management practices, much remains to be done. This presentation examines the use of fertilizers under the headings of the best management practice concept; right source, right application rate, right time of application, and right place. As fertilizer use will expand in the Mediterranean region, efficiency of use will be an underlying consideration. As agricultural land is on a global level is finite, with limited possibilities to expand cultivation, the increasing population of the world has correspondingly increased the needs for food and fibre. An inevitable development has been intensification of land use, particularly in developing countries of the world, leading to poverty and increased concerns about food security (Borlaug 2007). Pressure on land has been particularly acute in the arid and semi-arid regions, which are characterized by drought and land degradation. The lands surrounding the Mediterranean have been cultivated for millennia and are the site of settled agriculture and the center of origin of some of the world's major crops, especially cereals and pulses. Much development efforts have centered on the West Asia- North Africa (WANA) area, which is characterized by a Mediterranean climate and where drought is the main production constraint (Smith and Harris 1981).
  • Authors:
    • Thomas, R.
    • Aw-Hassan, A.
    • Turkelboom, F.
    • Bruggeman, A.
    • Rovere, R.
    • Al-Ahmad, K.
  • Source: Journal of Environment & Development
  • Volume: 18
  • Issue: 2
  • Year: 2009
  • Summary: This article reviews work that had the objective of introducing agricultural technologies in a marginal dryland area, the Khanasser Valley, northwestern Syria. The highly variable rainfall is barely sufficient to support livelihoods in this traditional barley-livestock production system. The valley is representative of other marginal dryland areas in West Asia and North Africa. We used a farmer-participatory approach to evaluate the performance of agricultural technologies for dry marginal areas in terms of their contribution to livelihoods and effect on the environment. The integrated approach allowed comprehensively comparing and evaluating the viability of promising technologies, including novel crops, intercropping, soil management techniques, and livestock rearing. The results show that improved barley varieties, olives, cumin, and lamb fattening can improve livelihoods, particularly for the land-owning households, whereas other households can benefit indirectly in terms of employment spillovers. These options are also environmentally friendly and sustain the natural resource base.
  • Authors:
    • Sabau, N. C.
    • Domuta, C.
    • Borza, I.
    • Bandici, G.
    • Samuel, A.
    • Ciobanu, C.
    • Ardelean ,I.
    • Ciobanu, G.
    • Sandor, M.
    • Domuta, C.
    • Brejea, R.
    • Vuscan, A.
  • Source: Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture
  • Volume: 66
  • Issue: 1
  • Year: 2009
  • Summary: Field studies were conducted in Oradea, Romania, from 2003 to 2008, in a long term trial placed in 1990 on preluvosoils. The climate indicator de Martonne aridity index (IdM) was used for quantification of the correlation between climate and wheat yield in unirrigated and irrigated conditions and a new class called arid was used for climate index characterization. Maintaining the soil water reserve on 0-50 cm depth between easily available water content and field capacity using the irrigation determined the increase of the IdM values for period IV-VI with 79% in 2003, 73% in 2004, 36% in 2005, 16% in 2006, 162% in 2007 and with 131% in 2008. Using the irrigation and the improvement of the microclimate conditions determined to obtain the yield gains, showed very significant results every year and every crop rotation studied, both in unirrigated and irrigated conditions. The smallest wheat yields were obtained in monocrop and the biggest in the wheat-maize-soyabean rotation. In the all 3 rotations, the direct links statistically assured were registered between the values of the IdM and yields in unirrigated and irrigated wheat. These correlations sustained the need of the irrigation in wheat from Crisurilor Plain. Correlation between the IdM was stronger in the wheat-maize-soyabean rotation compared to the wheat-maize rotation and with wheat monocrop. As a consequence, rotation of wheat-maize-soyabean was recommended because the climate and microclimate conditions were better used.
  • Authors:
    • Bara, C.
    • Sabau, N. C.
    • Domuta, C.
    • Borza, I.
    • Bara, V.
    • Samuel, A.
    • Ardelean, I.
    • Bara, L.
    • Ciobanu, G.
    • Sandor, M.
    • Domuta, C.
    • Brejea, R.
    • Vuscan, A.
  • Source: Analele Universităţii din Oradea, Fascicula: Protecţia Mediului
  • Volume: 14
  • Year: 2009
  • Summary: The paper is based on the research carried out during 2003-2008 in a long term trial placed in 1990 on the preluvosoil from Oradea. Climate indicator "de Martonne aridity index" (IdM) was used for quantification the correlation between climate and wheat yield in unirrigated and irrigated conditions and new class called "arid" was purposed for climate index characterization. Maintaining the soil water reserve on 0-50 cm depth between easily available water content and field capacity using the irrigation determined the increase of the IdM values for period IV-VI with 79% in 2003, 73% in 2004, 36% in 2005, 16% in 2006, 162% in 2007 and with 131% in 2008; using the irrigation and the improvement of the microclimate conditions determined to obtain the yield gains, very significant every year and every crop rotation studied; both in unirrigated conditions and in irrigated conditions, the smallest yields wheat were obtained in monocrop and the biggest in the wheat-maize-soybean crop rotation; in the all three crop rotation, the direct links statistically assured were registered between the values of the De Martonne aridity index and yields in unirrigated and irrigated wheat. These correlations sustain the need of the irrigation in wheat from Crisurilor Plain; correlation between De Martonne aridity index is stronger (R 2=0.7361 xx) in the wheat-maize-soybean crop rotation in comparison with wheat-maize crop rotation (R 2=0.6215 x) and with wheat monocrop (R 2=0.6105 x). As consequence, crop rotation of wheat-maize-soybean is recomanded because the climate and microclimate conditions are better use.
  • Authors:
    • Wasaya, A.
    • Asif, M.
    • Tanveer, A.
    • Nadeem, M. A.
    • Tahir, M.
    • Ali, A.
    • Jamil-ur-Rehman
  • Source: Pakistan Journal Of Life and Social Science
  • Volume: 7
  • Issue: 2
  • Year: 2009
  • Summary: In field experiment at Faisalabad, Pakistan conducted during August, 2005, the effect of different irrigation management strategies on growth and yield of soybean was investigated. The experiment comprised of eight irrigation practices of viz; rainfed, one irrigation at vegetative growth stage, one irrigation at flowering, one irrigation at pod formation, two irrigations at vegetative growth stage and at flowering, two irrigations at vegetative growth stage and at pod formation, two irrigations at flowering and at pod formation and three irrigations at vegetative growth stage, at flowering and at pod formation. Number of plants m -2, number of pods per plant, number of seeds per pod and seed yield was significantly higher when crop was irrigated with three irrigations at vegetative growth stage, at flowering and at pod formation.
  • Authors:
    • Janzen, H. H.
    • Ellert, B. H.
  • Source: Canadian Journal of Soil Science
  • Volume: 88
  • Issue: 2
  • Year: 2008
  • Summary: Irrigated land in southern Alberta is intensively managed, producing high yields but also requiring higher inputs, notably of nitrogen (N), than adjacent rainfed lands. The higher N inputs, combined with enhanced soil moisture, might stimulate nitrous oxide (N2O) emissions, but the influence of management on these emissions has not been widely studied. Our objective was to assess soil N2O emissions, along with those of carbon dioxide (CO2) and of methane (CH4), from irrigated cropping systems as influenced by source of N. We used a chamber technique to measure year-round emissions for 3 yr in long-term irrigated crop rotations receiving N as legume crop residues, non-legume crop residues, livestock manure or ammonium nitrate fertilizer. Unlike CO2 fluxes, which peaked during the growing season, those of N2O showed no consistent seasonal trends; emissions occurred sporadically in bursts throughout the year. Depending on management practices, 0.4 to 4.0 kg N2O-N ha(-1) yr(-1) was emitted to the atmosphere. The amount of N2O emitted from the alfalfa system, averaged over all manure and fertilizer N amendments, was more than twofold that emitted from the corn system. The proportions of fertilizer-N released as N2O were 0.95% for the alfalfa system and 1.30% for the corn system. After livestock manure or legume residues were incorporated, soil CO2 and N2O emissions appeared to be intertwined, but during the early spring N2O emissions were decoupled from CO2. Furthermore, N2O emissions were highly variable in space; at three of 54 chambers, N2O fluxes were consistently 12 to 55 times greater than those for other chambers in the same treatment. Such complexity conceals the underlying processes of net N2O production and transport to the soil surface.
  • Authors:
    • De Moura, R. L.
    • Klonsky, K. M.
    • Marsh, B. H.
    • Frate, C. A.
  • Source: University of California Cooperative Extension Publication
  • Year: 2008
  • Summary: Sample costs to produce grain corn (field corn for grain) in the southern San Joaquin Valley, California, USA, are shown in this study.
  • Authors:
    • Li, F.
    • Ma, Q.
    • Wang, Z.
    • Li, X.
  • Source: Soil & Tillage Research
  • Volume: 95
  • Issue: 1
  • Year: 2007
  • Summary: The effects of cultivation and overgrazing on soil quality in arid regions have been rarely addressed. This study investigated the roles of cropping and grazing in soil organic C pools and aggregate stability at 0-20 cm depth by comparing conventional grazing (non-fenced ever), intensive grazing (fenced for 22 years) and cropping (cultivated for 40 years) in the arid Hexi Corridor of northwestern China. Total soil organic C (TOC) under non-fenced grazing was 21.6 g kg-1 (or 52.9 Mg ha-1), which was 19.9% (or 13.2% mass per area) lower than that under fenced grazing, because of lower stable organic C fraction (0.25 mm) in total aggregates and mean weight diameter were 15% and 0.28 mm under cropping, significantly lower than 65% and 3.11 mm under non-fenced grazing and 65% and 2.84 mm under fenced grazing. The aggregates of >1 mm were almost entirely demolished under cropping when subjected to wet sieving. Reduction of soil carbohydrates under cropping was closely related to the decline in aggregate water-stability. The negative effects of cropping on soil organic C pool and aggregate water-stability may suggest that cropping on this arid grassland is not sustainable unless no-tillage is adopted. In favor of increasing soil carbohydrates and maintaining soil aggregation, fenced-grazing would be a better option than cropping and non-fenced grazing for the management of arid grasslands.
  • Authors:
    • Azarnivand, H.
    • Jafari, M.
    • Sharifani, F.
    • Abbasi, H.
    • Sori, M.
  • Source: Iranian Journal of Range and Desert Research
  • Volume: 13
  • Issue: 4
  • Year: 2007
  • Summary: The effects of plant growth on soil quality in the Sagzi plain of Isfahan (Iran) were determined to evaluate the influence of agriculture on the desertification processes in dry lands. Inappropriate crop management significantly affected soil and water salinization which is one of the important processes of desertification. To determine if agriculture is a positive or negative factor for the reclamation of saline soils, improved and degraded factors of desertification in Sagzi plain of Isfahan were considered. Medicago, wheat and barley were evaluated to determine which crop is more effective for soil reclamation. Wheat and barley were selected and compared with derelict land, which was and independent variable in this study. The soils considered were cultivated with these products successively for at least 5 years. Soil samples were then obtained at different depths (0-3, 30-60, 60-90, 90-120, 120-150 cm) and were analysed for CaCO 3, electrical conductivity, organic matter, K +, Mg +, Ca 2+, Na +, CaSO 4, Cl -, sodium adsorption ratio, HCO 3- and SO 4-. Variance analysis showed significant difference between treatments at different depths and that among the three crops, wheat cropping is the best for soil reclamation.