• Authors:
    • Deckers, J.
    • Govaerts, B.
    • Nyssen, J.
    • Araya, T.
    • Cornelis, W. M.
  • Source: Soil and Tillage Research
  • Volume: 148
  • Year: 2015
  • Summary: Field water conservation practices are a way to build resilience against drought by increasing productive green water through reducing runoff and evaporation and thereby boosting crop yield. A field study was undertaken on permanently kept rainfed experimental plots established in 2005 on a vertisol in order to evaluate two resource saving cropping systems based on conservation agriculture (CA) that integrate in situ soil and water conservation tillage practices (derdero+ and terwah+) as compared to a conventional system in terms of soil moisture, runoff, water loss (drainage and evapotranspiration together), water productivity and crop yield. The experimental layout was a randomized complete block design with three replications and a plot size of 5m×19m. The farming systems differed in tillage practice, but all had wheat, teff, barley and grass pea crops grown in rotation. The tillage treatments were (i) derdero+ (DER+) with a furrow and permanent raised bed planting system, plowed only by refreshing the furrow once at planting with no tillage on top of the permanently kept raised beds, 30% standing crop straw retention, and with ~20% of the crop residue being covered with soil during refreshing the furrow at planting, (ii) terwah+ (TER+) with furrows made at 1.5m intervals, plowed once at planting, 30% standing crop straw retention and fresh broad beds, and crop residue being partly covered with soil during tillage at planting, and (iii) conventional tillage (CT) with a minimum of three plain tillage operations and complete removal of crop straw. All plowing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plow called mahresha. Glyphosate was sprayed at 2lha-1 to control weeds before crop emergence, starting from 2007 with DER+ and TER+. Runoff was collected at the lower end of each plot in calibrated runoff collectors after each runoff event. Soil-water content was measured using the gravimetric method at 5-6 day intervals. Normalized Difference Vegetation Index (NDVI) was measured in the field at several phenological stages, using a handheld GreenSeeker™ Optical Sensor Unit. Soil-water storage (0-80cm soil depth) during the growing season was always highest with DER+ followed by TER+ and CT, whereas the opposite trend was observed for runoff. On the other hand, deep drainage and evapotranspiration was always highest in the DER+ compared to CT. NDVI records throughout the growing season were significantly highest with DER+ for wheat and grass pea, while the highest values were observed with TER+ when under teff. These values were directly proportional to the above ground crop biomass and yield. The grain and straw yield of wheat in 2009 was increased from 1.6 and 3.7tha-1 with CT to 2.6 and 5.2tha-1 with DER+, respectively. Our study demonstrates that field water conservation tillage practices that incorporate CA principles are effectively increasing green water in the root zone available for crops and thus, improve crop productivity and yields substantially on vertisols in drylands without other inputs.
  • Authors:
    • Wambua, J. M.
    • Mungube, E. O.
    • Njiru, E. N.
    • Gatheru, M.
    • Gichangi, E. M.
    • Wamuongo, J. W.
  • Source: Article
  • Volume: 130
  • Issue: 2
  • Year: 2015
  • Summary: A study was conducted to investigate the intra-seasonal climate variability and change in semi-arid eastern Kenya and also assessed the ability of the households to discern trends in climate and how the perceived trends converge with actual long term weather observations. The study utilised long term climatic data and data collected through interviews of 200 households using a structured questionnaire. The survey data was analysed through descriptive statistics using the Statistical Package for Social Sciences (SPSS) version 12.0. The results of long term climatic data indicated high year-to-year variation in seasonal rainfall with 49.0% and 58% negative anomalies observed in the long and short rainfall seasons respectively. No discernible increasing or decreasing trend in the long- seasonal rainfall was observed over the period of study. However, Long-term temperature data showed high year-to-year variation in annual mean maximum and minimum temperatures with maximum temperature increasing during the period. Long term rainfall data (51 years) showed that 31.4 and 35.3% of the long rains would be classified as good and failed seasons respectively, with the remaining percentage classified as moderate seasons. For the short rains, 15.7 and 43.1 % would be classified as good and failed seasons respectively, with the remaining percentage classified as moderate seasons. Farmers interviewed were able to recollect the past seasons fairly accurately especially the 'good' and 'failed' seasons which corroborated well with the meteorological records. Indigenous knowledge on weather forecasting was reported by 81% of farmers to be helpful in farming decision making especialy on the types of crops to be planted. A better understanding of farmers' perceptions of climate change, ongoing adaptation measures, and the decision-making process would important to inform policies aimed at promoting sustainable adaptation of the agricultural sector.
  • Authors:
    • QiFe, H.
    • Luo GePing
    • Madaminov, A. A.
    • Maisupova, B.
    • Chen, X.
    • Zhang, C.
    • Li, C.
    • Djenbaev, B. M.
  • Source: Primary Research Article
  • Volume: 21
  • Issue: 5
  • Year: 2015
  • Summary: Central Asia has a land area of 5.6*10 6 km 2 and contains 80-90% of the world's temperate deserts. Yet it is one of the least characterized areas in the estimation of the global carbon (C) stock/balance. This study assessed the sizes and spatiotemporal patterns of C pools in Central Asia using both inventory (based on 353 biomass and 284 soil samples) and process-based modeling approaches. The results showed that the C stock in Central Asia was 31.34-34.16 Pg in the top 1-m soil with another 10.42-11.43 Pg stored in deep soil (1-3 m) of the temperate deserts. They amounted to 18-24% of the global C stock in deserts and dry shrublands. The C stock was comparable to that of the neighboring regions in Eurasia or major drylands around the world (e.g. Australia). However, 90% of Central Asia C pool was stored in soil, and the fraction was much higher than in other regions. Compared to hot deserts of the world, the temperate deserts in Central Asia had relatively high soil organic carbon density. The C stock in Central Asia is under threat from dramatic climate change. During a decadal drought between 1998 and 2008, which was possibly related to protracted La Nina episodes, the dryland lost approximately 0.46 Pg C from 1979 to 2011. The largest C losses were found in northern Kazakhstan, where annual precipitation declined at a rate of 90 mm decade -1. The regional C dynamics were mainly determined by changes in the vegetation C pool, and the SOC pool was stable due to the balance between reduced plant-derived C influx and inhibited respiration.
  • Authors:
    • Hanewinkel, M.
    • Yousefpour, R.
  • Source: Article
  • Volume: 130
  • Issue: 2
  • Year: 2015
  • Summary: Forestry professionals' perceptions of the risks and uncertainties associated with climate change were investigated in a questionnaire survey in south-west Germany. The respondents were employed in forestry in either public or private forests or working for state authorities. They were specifically asked about the related impacts of climate change on forest ecosystems, adaptive forest management and the potential of forestry to mitigate climate change. A factor analysis of the responses revealed significant variables explaining the major part of the variance and the key variable groups were identified in a canonical analysis. The majority of respondents (72 %) said they were under-informed, but most (83 %) view climate change as a reality, human-caused, and a significant risk. These forestry professionals were particularly concerned about extreme hazards, water scarcity, and changes in climatic zones. They generally said the potential of forestry to mitigate climate change is low, and saw few realistic measures like increased harvesting to substitute fossil fuels and energy-intensive materials for mitigation. Despite the uncertainty involved, adaptation strategies like using better-adapted tree species and provenances were mainly perceived as helpful, and tools such as spatially-explicit maps with recommendations for adapted species and indices of biotic and abiotic risks as important. The forestry professionals reported obtaining their information about climate change from advanced forestry training, the media, and scientific literature. The findings of the study are discussed in the light of the ongoing debate on climate change in Germany and recommendations made, including periodically checking and improving forestry professionals' knowledge about climate change.
  • Authors:
    • Buerkert, Andreas
    • Bruentrup, Michael
    • Lamers, John P. A.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 1
  • Year: 2015
  • Summary: Low concentrations of phosphorus (P) also limit crop production on the acid, sandy soils in Sudano-Sahelian West Africa (SSWA). An increased P-use is thus a key leverage for enhancing food security and alleviating poverty. Therefore, P-imports into the predominating agro-pastoral farming systems are indispensable, but most smallholders are cash-poor and risk averse, face labor-constraints, and P-fertiliser responses are site-specific. Key to the adoption of any new technology is a high financial performance with low risk levels of failure, low demands of labor and cash, and adaptation to the prevailing farming systems. Financial performances were assessed from nine, annually applied fertilising practices during 4 years in five SSWA zones. Information about the farming systems, labor demands, and input-output prices stem from secondary sources. The profitability largely depended on rainfall and location-specific soil conditions, but those of annually repeated mineral and organic P-strategies increased over time. Several P-fertilisations were profitable on a per land unit basis, but could not compete with farmers' practices on a per labor unit basis. Mulching with and without P (13 kg P ha(-1)) were not financially superior, but the broadcast application of 13 kg P ha(-1) became profitable over time. Hill-placed P (4 kg P ha(-1)), also known as micro-dosing, was a profitable alternative to farmers' practices particularly in the intermediate rainfall zone. The results showed the importance of recommendations following rainfall zones, which are of interest across a spectrum of users including policy makers, land use practitioners, private firms, NGOs and research for development implementers.
  • Authors:
    • Wang HongLan
    • Tang XiangYu
    • Zhang Wei
    • Liu Chen
    • Guan Zhuo
    • Xiao Liang
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 31
  • Issue: 4
  • Year: 2015
  • Summary: Biochar is a kind of solid residual produced by thermal decomposition of organic material under limited or absent supply of oxygen, and relatively low temperatures, biochar has the properties of high internal surface area and microporosity, furthermore, non-biological and biological stability. It used as a soil amendment could greatly improve soil physical and chemical properties, reduce the biological effectiveness of soil pollutant and greatly reduce the emission of carbon dioxide and other greenhouse gases and sequestrated soil carbon in recent years. In this study, a one-year field trail of biochar application in the hilly area of central Sichuan Basin, was carried out in sloping farmland plots, which was located at Yanting Agro-ecological Experimental Station of Purple Soil (105°27′E, 31°16′N), Sichuan, Southwest China, to investigate the effects on hydraulic properties of cultivated purple soil (an entisol). Two treatments were set up: control (NPK) and biochar amended (NPK-BC), with each being replicated three times. Comparison between biochar amended and control plots was made by determining soil hydraulic parameters, soil pore size distribution and the contribution of each pore size to flow at two depths (2-7 and >7-12 cm) of the plough layer. Results showed that: (1) due to biochar application, the soil contact angle was increased by 6.7° and 0.5° at the 2-7 and >7-12 cm depth, respectively. This implies that soil water absorption ability was increased and nutrients will be more easily dissolved in the soil. (2) After one year of biochar application, the residual water content (theta r), which is unavailable to plants and water content in structure pores (theta str), which is easy to be drained out, was decreased, respectively. But the water content in soil matrix pores (theta txt), which is available to plants, increased significantly ( P125 m pores increased by 54% and 8% at the 2-7 and >7-12 cm depth, respectively. Particularly, the effective porosity of r>500 m pores increased most markedly, reaching 110% and 355% for the two depths, respectively. This shows that biochar application reduces the 250 125 m pores increased by 54% and 8% at the 2-7 and >7-12 cm depth, respectively. Particularly, the effective porosity of r>500 m pores increased most markedly, reaching 110% and 355% for the two depths, respectively. This shows that biochar application reduces the 250 125 m pores increased by 54% and 8% at the 2-7 and >7-12 cm depth, respectively. Particularly, the effective porosity of r>500 m pores increased most markedly, reaching 110% and 355% for the two depths, respectively. This shows that biochar application reduces the 250 125 m pores increased by 54% and 8% at the 2-7 and >7-12 cm depth, respectively. Particularly, the effective porosity of r>500 m pores increased most markedly, reaching 110% and 355% for the two depths, respectively. This shows that biochar application reduces the 250 500 m); (4) the saturated hydraulic conductivity at the two depths (2-7 and >7-12 cm) increased by 45% and 35%, respectively, after a year of biochar application. Tension infiltration data show that soil macropores ( r>125 m) were the main contributing (accounting for 92-94%) pores to the fast drainage at the 2-7 and >7-12 cm depth, under control and biochar amended r, in spite of their very low percentage (3-4%) of total porosity. (5) Therefore, it can be inferred that, on one hand, the application of biochar could increase the soil's capacity to hold plant-available water and thus enhance resistance to drought; on the other hand, it can also enhance water permeability of soil, which can reduce surface runoff and potential soil erosion.
  • Authors:
    • Evans,Jason M.
    • Calabria,Jon
    • Borisova,Tatiana
    • Boellstorf,Diane E.
    • Sochacka,Nicki
    • Smolen,Michael D.
    • Mahler,Robert L.
    • Risse,L. Mark
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: A growing body of research indicates that opinions about long-term climate change and other natural resource issues can be significantly affected by current weather conditions (e.g., outside air temperature) and other highly contingent environmental cues. Although increased severity and frequency of droughts is regarded as a likely consequence of anthropogenic climate change, little previous research has attempted to relate the experience of drought with public attitudes about water supply or water-related climate change issues. For this study, a large set (n = 3,163) of public survey data collected across nine states of the southern United States was spatio-temporally linked with records of short-term (similar to 12 weeks) and long-term (similar to 5 years) drought condition at the level of each respondent's zip code. Multivariate ordinal logistic regression models that included numerous other independent variables (environmental ideology, age, gender, education, community size, residency duration, and local annual precipitation) indicated highly significant interactions with long-term drought condition, but showed no significant effect from short-term drought condition. Conversely, attitudes about water-related climate change showed highly significant interactions with short-term drought, with weaker to no effects from long-term drought. While the finding of significant effects from short-term drought condition on opinions about future drought is broadly consistent with previous public opinion research on climate change, the finding of water supply attitudes being more responsive to longer term drought condition is, to our knowledge, a novel result. This study more generally demonstrates the methodological feasibility and applied importance of accounting for local drought condition when public opinion information is used to evaluate outreach programs for water conservation and climate change.
  • Authors:
    • Turner, N. C.
    • Fu, T. T
    • Wang, Y. P.
    • Hai, L.
    • Li, X. G.
    • Liu, X. E.
    • Li, F. M.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 4
  • Year: 2014
  • Summary: Alleviating the hydrothermal limitations to growth, clear film fully mulched ridge-furrow (FMRF) cropping significantly improves maize (Zea mays L.) grain yield on the Loess Plateau of China. Major concerns for FMRF cropping are the stability of maize productivity and whether the system is detrimental to the soil organic C (SOC) balance under changed hydrothermal conditions. We investigated the effects of maize production with FMRF and its effect on SOC concentration for five consecutive years from 2008 to 2012. Three treatments were imposed: no mulch (narrow ridges with the crop sown beside the ridges), half mulch (the same as no mulch, except the narrow ridges were mulched), and full mulch (i.e., FMRF; alternate narrow and wide ridges, all mulched, with maize in furrows). The 5-yr average of the grain yield was 3.8 Mg ha -1 under no mulch. Half and full mulch increased the grain yield by 68 and 102%, respectively, relative to no mulch. Root biomass was 69 and 104% greater under half and full mulch, respectively, than no mulch. The maize yield and biomass differed among years depending on the growingseason precipitation and its distribution, but the increased yield and biomass from mulching was consistent in all years. The mulch stimulated SOC mineralization and enzymatic activity but had no effect on light (density <1.8 gcm-3) and total SOC concentrations compared with no mulch. We conclude that increased SOC mineralization under FMRF was offset by increased SOC addition; FMRF cropping increased maize productivity without detriment to the SOC balance. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved.
  • Authors:
    • Liang, L.
    • Jia, Z.
    • Wang, X.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 5
  • Year: 2014
  • Summary: Field experiments were conducted from 2008 to 2010 in the Weibei Highlands of China to study the effects of straw incorporation on soil moisture, evapotranspiration (ET), and rainfall-use efficiency (RUE) of maize (Zea mays L.) under semiarid conditions in dark loessial soil. The straw application rates were at low straw ([LS] 4.5 t ha(-1)), medium straw ([MS] 9 t ha(-1)), and high straw ([HS] 13.5 t ha(-1)) rates combined with fixed levels of chemical fertilizers compared with only chemical fertilizers. Straw incorporation significantly increased surface soil moisture at the grain filling stage of maize and significantly improved RUE in the whole growth period of maize. Evapotransipiration at the ten leaf collar to tasseling and the grain filling to maturity stages of maize were significantly increased by straw incorporation. However, ET at the tasseling to grain filling stage of maize was significantly reduced by straw incorporation. Medium straw and HS treatments significantly improved surface soil moisture at the tasseling stage of maize and RUE at the five leaf collar to maturity stage of maize. Increasing straw application rates significantly reduced ET at the grain filling to maturity stage of maize. With increasing experimental years, LS treatment significantly improved surface soil moisture at the five leaf collar to tasseling stage of maize and RUE at the five and ten leaf collar stage of maize, MS treatment significantly increased surface soil moisture at the five and ten leaf collar stages of maize, and HS treatment significantly reduced ET at the sowing to five leaf collar stage of maize. We conclude that a reasonable combination application of straw and chemical fertilizers could make full use of surface soil moisture, inhibit soil evaporation, reduce the ineffective evaporation of crop, and increase RUE at a different growth period of maize and grain yield. In this experiment, the optimum straw application rate for improving RUE and grain yield was MS treatment.
  • Authors:
    • Robertson, R. D.
    • Mueller, C.
  • Source: Agricultural Economics
  • Volume: 45
  • Issue: 1
  • Year: 2014
  • Summary: Assessments of climate change impacts on agricultural markets and land-use patterns rely on quantification of climate change impacts on the spatial patterns of land productivity. We supply a set of climate impact scenarios on agricultural land productivity derived from two climate models and two biophysical crop growth models to account for some of the uncertainty inherent in climate and impact models. Aggregation in space and time leads to information losses that can determine climate change impacts on agricultural markets and land-use patterns because often aggregation is across steep gradients from low to high impacts or from increases to decreases. The four climate change impact scenarios supplied here were designed to represent the most significant impacts (high emission scenario only, assumed ineffectiveness of carbon dioxide fertilization on agricultural yields, no adjustments in management) but are consistent with the assumption that changes in agricultural practices are covered in the economic models. Globally, production of individual crops decrease by 10-38% under these climate change scenarios, with large uncertainties in spatial patterns that are determined by both the uncertainty in climate projections and the choice of impact model. This uncertainty in climate impact on crop productivity needs to be considered by economic assessments of climate change.