• Authors:
    • Sanderman, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 155
  • Year: 2012
  • Summary: In many important agricultural regions, soil inorganic carbon (SIC) stocks can rival the amount of carbon found in organic form. land management practices, including irrigation, fertilization and liming, have the potential to greatly alter the soil inorganic carbon cycle thus creating an important feedback to atmospheric CO2 concentrations. However, the current literature is less clear regarding the direction and magnitude of this feedback. Application of irrigation water, for example, can increase the rate of soil carbonate precipitation, but depending on the source of calcium and bicarbonate, the net reaction can be an atmospheric carbon sink, a carbon source or carbon neutral. Similarly, the accelerated dissolution of soil carbonates due to various acidifying processes can act as a net sink or source of atmospheric CO2 depending on the spatial and temporal frame of reference. While SIC stocks in agricultural soils have been found to increase or decrease by as much as 1.0 t C ha(-1) yr(-1), given the need to account for both the supply and fate of reactants and reaction products, ascribing these stock changes as a net sink or net source activity is difficult. This review paper provides an overview of the major inorganic carbon transformations in soils as affected by agricultural management, including the practice of liming to raise soil pH, and when these transformations should be considered a net atmospheric carbon source or sink. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Kumari, S.
  • Source: Journal of Agricultural Science
  • Volume: 4
  • Issue: 1
  • Year: 2012
  • Summary: This study critically assessed the influence of frequent availability of water i. e. drip irrigation and mulch on optimum leaf area development of potato that control light interception and soil moisture conservation. Crop growth was stimulated in terms of early pick up of leaf areas that quickly covered the ground and improved transpiration efficiency. Drip irrigation increased water use efficiency three times as compared with furrow irrigation (conventional method of irrigation). Black Polyethylene mulch (25 m) conserved soil moisture, raised soil temperature by 9degreesC, stimulated shoot, solon and root growth, increased the total tuber number and yield but reduced the grade of tubers. Drip irrigation may prove a viable tool for source-sink alteration; stimulating early stolon initiation combined with ability to quick ground cover and sustained leaf growth for new tuber initiation for seed production as well as extended tuber bulking of early formed tubers for obtaining maximum yield with 50% saving of irrigation water and efficient use of nitrogen fertilizer.
  • Authors:
    • Schlegel, A.
    • Halvorson, A.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 5
  • Year: 2012
  • Summary: Limited irrigation management practices are being used in the Central Great Plains to conserve water by optimizing crop water use efficiency. Limited irrigation may reduce total crop biomass production and amount of crop residue returned to the soil. Crop residue production within four no-till (NT) crop rotations [continuous corn ( Zea mays L.) (CC); corn-winter wheat ( Triticum aestivum L.) (CW); corn-winter wheat-grain sorghum ( Sorghum bicolor L. Moench) (CWS); corn-winter wheat-grain sorghum-soybean [ Glycine max (L.) Merr.] (CWSSb)] was measured and changes in soil organic carbon (SOC) and total soil nitrogen (TSN) stocks were monitored for 10 yr. Crop residue yields varied with crop being produced and with rotation, as did residue N and C returned to the soil. The C/N ratio of the residue varied with crop. The SOC and TSN pools increased with time in all rotations. The rate of gain in SOC and TSN mass for each rotation was 717, 477, 335, and 270 kg SOC ha -1 yr -1 and 114, 92, 87, and 84 kg TSN ha -1 yr -1 for the CC, CW, CWS, and CWSSb rotations, respectively, in the 0- to 30.5-cm soil depth. The rate of change in SOC and TSN mass was lowest with CWSSb (8.7 Mg residue ha -1 yr -1) and highest with CC (12.0 Mg residue ha -1 yr -1). Approximately 6.8 to 7.6 Mg residue ha -1 yr -1 would be needed to maintain SOC stocks under limited irrigation.
  • Authors:
    • Kannan, K.
    • Verma, H.
    • Mishra, A.
  • Source: Irrigation and Drainage
  • Volume: 61
  • Issue: 3
  • Year: 2012
  • Summary: A model was developed to modify the canal delivery schedule of a major irrigation project of eastern India for both monsoon and dry seasons that adopted the procedure of daily water balance/moisture balance simulation in the root zone depth. In addition to the prevailing continuous schedule, four alternative rotational schedules during the monsoon and five alternative rotational schedules during the dry season were considered for simulation. Daily water balance simulation was performed for 17 and 15 years for the monsoon season and the dry seasons, respectively. Simulation results for the monsoon revealed that a 15-day rotational schedule (15 days canal operation followed by 15 days canal closure) was the best alternative over the prevailing continuous schedule. To agree with the findings of the study model, field experiments were conducted during the monsoon season for three consecutive years. Highest rice grain yields of 4.92 t/ha ( Swarna) and 4.46 t/ha ( Surendra) were recorded in plots with 15-day rotational schedules. During the dry season, considering both paddy and other dry season crops grown together in the command, a 7-day canal operation followed by a 7-day canal closure rotational schedule was found to be the best alternative. Besides creating a favourable water regime and better crop evapo-transpiration (ET), this schedule saved about 10.3% of water over actual water supplies.
  • Authors:
    • Lordian, Anna
    • Borisover, Mikhail
    • Levy, Guy J.
  • Source: GEODERMA
  • Volume: 179
  • Year: 2012
  • Summary: Use of treated wastewater (TWW) for irrigation may affect the concentration and composition of dissolved organic matter (DOM) in the soil solution. Our objectives were (i) to characterize the water-extractable fraction of soil organic matter (SOM) in terms of chromophoric DOM (CDOM) for different soil types and irrigation water qualities, and (ii) to examine the possible relations between DOM composition and various soil properties. Aqueous extracts from four different soil types irrigated with either secondary TWW or fresh water (FW) were characterized for dissolved organic carbon (DOC) concentration and absorbance at 254 nm (Abs(254)). Excitation-emission matrices (EEM) of fluorescence were determined in these aqueous extracts and in extracts where DOM was separated into acid-soluble and acid-precipitated fractions. Parallel factor (PARAFAC) analysis of the EEMs of water-extractable DOM and their fractions identified two humic-like fluorescent components and one tryptophan-like component and provided their concentration scores. The concentration scores revealed that the acid-soluble DOM fraction contained the greater part of the humic-like fluorescent components present in the bulk DOM samples. Statistical examination demonstrated that the ratio of the concentration score of the humic-like substances that emit light at shorter wavelengths to that of humic-like substances that emit light at longer wavelengths was higher in the acid-soluble DOM fraction compared to the acid-precipitated DOM fraction. Among the FW-irrigated soils, the soil extracts varied in terms of concentration of DOM components. Irrigation of the coarse-textured soils with TWW generally increased the concentrations of DOC, fluorescent components and Abs(254) in comparison to irrigation with FW. In the fine textured soils TWW application led to a decrease or had no impact on the concentration of DOC and the CDOM components in water-extractable SOM. Thus, the influence of TWW irrigation on water-soluble SOM relative to that of FW irrigation was also soil dependent. Strong linear relations (/r/>0.7) were found within CDOM indicators including concentration scores of fluorescent components and Abs(254). Weak or no relations were found (i) between DOC concentration and CDOM indicators, and (ii) between attributes related to DOM properties and basic soil properties. Hence. nor DOC concentration neither SOM content can be used for estimating changes in concentrations of chromophoric components in water-extractable DOM. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Luo, J. F.
    • Ding, W. X.
    • Cai, Y. J.
  • Source: GEODERMA
  • Volume: 181
  • Year: 2012
  • Summary: There is a high spatial variation in N2O emission from agricultural fields and N2O emissions from fields cultivated with stalk-crops was generally measured in the interrow area. The aim of this study was to evaluate the difference in seasonal N2O emissions between interrow soil and interrow + row soil, and to understand the effect of different fertilizers on N2O emissions in a maize-cultivated sandy loam soil in the North China Plain. The experiment included five treatments: organic manure (OM), half-organic manure N plus half fertilizer N (HOM), fertilizer NPK (NPK), fertilizer NK (NK) and control (CK). Cumulative N2O emission from interrow + row soil during the maize growth season was 0.84-122 kg N ha(-1) with an average of 0.98 kg N ha(-1) in the N-fertilized treatments, significantly higher than the 0.30-0.49 kg N ha(-1) from interrow soil. However, no significant difference was observed in the CK treatment. The measurement in interrow soil underestimated N2O emissions by 44-67%. This difference mainly occurred at the two peak emission periods following fertilizer application probably due to discrepancy in soil denitrification potential. Manure application more efficiently increased difference in N2O emission between interrow soil and interrow + row soil than inorganic N fertilizer application. The higher NO concentration did not induce larger N2O emission from interrow soil in the NK treatment than in the NPK treatment, but did from interrow + row soil, resulting in greater difference in N2O emission between interrow soil and interrow + row soil. It is suggested that measuring N2O emission solely from interrow soil could underestimate seasonal N2O emissions, and partly mask the effect of N fertilizer application rates on N2O emission in a maize-cultivated soil in the North China Plain.
  • Authors:
    • Awo, M.
    • Schraven, B.
    • Laube, W.
  • Source: CLIMATIC CHANGE
  • Volume: 111
  • Issue: 3-4
  • Year: 2012
  • Summary: Climate change and land degradation result in decreasing yields and crop failures in Northern Ghana and have caused further impoverishment of Ghana's poorest region. Farmers have diversified their livelihoods to adapt to uncertain environmental conditions in various ways. While traditionally a diversification of the production and migration were the prime means of adaptation, many farmers have started to intensify their production by adopting shallow groundwater irrigation for vegetable gardening for Ghana's urban markets. This has helped to cope with a changing environment, ameliorated poverty and reversed rural-urban migration, while the local hydrology curbed an over-exploitation of groundwater resources, commonly associated with an uncontrolled farmer-driven expansion of groundwater irrigation. This research confirms that farmer-driven small-scale irrigation can play an important role in the process of climate change adaptation. However, while farmers tried to integrate in the larger economy, they have become subject to market failures that in their essence are caused by unfair and unpredictable patterns of global trade. It is this double exposure to global environmental change and economic globalization that need to be taken into consideration when local adaptive capacities are discussed. Many convincing arguments call for the revision of some of the most unfair and devastating economic practices; however, the need to enhance adaptive capacity towards global climate change for poor parts of the population in the south should be added to the discussion.
  • Authors:
    • Samarasinghe, S.
    • Safa, M.
  • Source: Environmental Pollution
  • Volume: 171
  • Issue: December
  • Year: 2012
  • Summary: This review paper concentrates on carbon dioxide emissions, discussing its agricultural sources and the possibilities for minimizing emissions from these sources in wheat production in Canterbury, New Zealand. This study was conducted over 35,300 ha of irrigated and dryland wheat fields in Canterbury. Total CO2 emissions were 1032 kg CO2/ha in wheat production. Around 52% of the total CO2 emissions were released from fertilizer use and around 20% were released from fuel used in wheat production. Nitrogen fertilizers were responsible for 48% (499 kg CO2/ha) of CO2 emissions. The link between nitrogen consumption, CO2 emissions and crop production showed that reducing the CO2 emissions would decrease crop production and net financial benefits to farmers. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Caesar, A.
    • Caesar-TonThat, T.
    • Sainju, U. M.
  • Source: Soil and Tillage Research
  • Volume: 118
  • Issue: January
  • Year: 2012
  • Summary: Portable chamber provides simple, rapid, and inexpensive measurement of soil CO2 flux but its effectiveness and precision compared with the static chamber in various soil and management practices is little known. Soil CO2 flux measured by a portable chamber using infrared analyzer was compared with a static chamber using gas chromatograph in various management practices from May to October 2008 in loam soil (Luvisols) in eastern Montana and in sandy loam soil (Kastanozems) in western North Dakota, USA. Management practices include combinations of tillage, cropping sequence, and N fertilization in loam and irrigation, tillage, crop rotation, and N fertilization in sandy loam. It was hypothesized that the portable chamber would measure CO2 flux similar to that measured by the static chamber, regardless of soil types and management practices. In both soils, CO2 flux peaked during the summer following substantial precipitation and/or irrigation (>15 mm), regardless of treatments and measurement methods. The flux varied with measurement dates more in the portable than in the static chamber. In loam, CO2 flux was 14-87% greater in the portable than in the static chamber from July to mid-August but 15-68% greater in the static than in the portable chamber from late August to October in all management practices. In sandy loam, CO2 flux was 10-229% greater in the portable than in the static chamber at all measurement dates in all treatments. Average CO2 flux across treatments and measurement dates was 9% lower in loam but 84% greater in sandy loam in the portable than in the static chamber. The CO2 fluxes in the portable and static chambers were linearly to exponentially related (R-2 = 0.68-0.70, P < 0.01, n = 40-56). Although the trends of CO2 fluxes with treatments and measurement dates were similar in both methods, the flux varied with the methods in various soil types. Measurement of soil CO2 flux by the portable chamber agreed more closely with the static chamber within 0-10 kg C ha(-1) d(-1) in loam soil under dryland than in sandy loam soil under irrigated and non-irrigated cropping systems. Published by Elsevier B.V.
  • Authors:
    • Liebig, M. A.
    • Caesar-TonThat, T.
    • Stevens, W. B.
    • Sainju, U. M.
  • Source: Journal of Environmental Quality
  • Volume: 41
  • Issue: 6
  • Year: 2012
  • Summary: Management practices, such as irrigation, tillage, cropping system, and N fertilization, may influence soil greenhouse gas (GHG) emissions. We quantified the effects of irrigation, tillage, crop rotation, and N fertilization on soil CO2, N2O, and CH4 emissions from March to November, 2008 to 2011 in a Lihen sandy loam in western North Dakota. Treatments were two irrigation practices (irrigated and nonirrigated) and five cropping systems (conventional-tilled malt barley [Hordeum vulgaris L.] with N fertilizer [CT-N], conventional-tilled malt barley with no N fertilizer [CT-C], no-tilled malt barley pea [Pisum sativum L.] with N fertilizer [NT-PN], no-tilled malt barley with N fertilizer [NT-N], and no-tilled malt barley with no N fertilizer [NT-C]). The GHG fluxes varied with date of sampling and peaked immediately after precipitation, irrigation, and/or N fertilization events during increased soil temperature. Both CO2 and N2O fluxes were greater in CT-N under the irrigated condition, but CH4 uptake was greater in NT-PN under the nonirrigated condition than in other treatments. Although tillage and N fertilization increased CO2 and N2O fluxes by 8 to 30%, N fertilization and monocropping reduced CH, uptake by 39 to 40%. The NT-PN, regardless of irrigation, might mitigate GHG emissions by reducing CO2 and N2O emissions and increasing CH4 uptake relative to other treatments. To account for global warming potential for such a practice, information on productions associated with CO2 emissions along with N2O and CH4 fluxes is needed.