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401.
Jessica Sosa‐Quintero Hctor Godínez‐Alvarez 《Land Degradation u0026amp; Development》2019,30(5):494-503
The impacts of human activities on temperate and subtropical deserts have been evaluated worldwide. However, data about tropical deserts are scarce. In this study, we evaluated the impacts of rainfed agriculture and firewood extraction on vegetation and soil of abandoned croplands (mesquite cropland and goldeneye cropland) and mesquite shrublands (open‐canopy mesquite and closed‐canopy mesquite) in a tropical Mexican desert. We interviewed peasants to understand their management practices and evaluated vegetation traits and soil properties of sites. We also examined the impacts of land management on vegetation and soil with structural equation modeling. Rainfed agriculture consisted of cultivating crops, fertilizing with manure, and introducing goats to croplands after harvest. Goldeneye cropland had higher canopy cover, vegetation structure, and litter cover than mesquite cropland. However, soil in both croplands was highly compacted with low infiltration rate, organic matter, and nutrient content. Firewood extraction only consisted of removing mesquite branches. Open‐canopy mesquite had lower canopy and litter cover and higher biological soil crust cover than closed‐canopy mesquite. The soil in both shrublands was less compacted with relatively high infiltration rate, organic matter, and nutrient content. Rainfed agriculture decreased soil nutrient content due to removal of native vegetation, plowing, and goat introduction to croplands. In contrast, firewood extraction maintained a relatively high soil nutrient content because branch removal enables the establishment of biological soil crusts, which increased the infiltration rate and nutrient availability. Thus, firewood extraction has a lower impact on the structure and function of fluvial terraces than rainfed agriculture in this tropical desert. 相似文献
402.
Agricultural productivity in the highlands of Ethiopia is threatened by severe land degradation, resulting in significant reductions in agricultural GDP. In order to mitigate ongoing erosion and soil nutrient loss, the government of Ethiopia initiated a Sustainable Land Management Program (SLMP) targeting 177 micro‐watersheds in six regions of the Country. This study evaluates the impact of SLMP on the value of agricultural production across diverse agro‐ecological zones by using a panel survey from 2010 to 2014. Results suggest the need for long‐term engagement in SLM activities regardless of underlying biophysical endowments and environmental characteristics. The analysis finds that the SLMP is not associated with significant increases in household‐level agricultural value of production after 4 years of program participation regardless of agro‐ecological zone or landscape type. However, SLM investments and agricultural value of production increased significantly in both treatment and nontreatment areas between 2010 and 2014. Although data suggest positive trends in agricultural productivity and SLM activities during program years, past soil and water conservation programs in Ethiopia have failed to maintain momentum in rural communities after programs ceased funding. Given the results presented in this paper, SLM programs should place emphasis on SLM infrastructure maintenance over the medium to long term in order to reap sustainable effects of SLM on agricultural productivity in critical watersheds. 相似文献
403.
Zhigang Li Rebecca L. Schneider Stephen J. Morreale Yingzhong Xie Jian Li Changxiao Li Xilu Ni 《Land Degradation u0026amp; Development》2019,30(11):1313-1324
Solutions are urgently needed to address the continued degradation of agricultural soils worldwide, which has severely impacted the ability to grow crops and has led to increased irrigation demand from already rapidly depleting freshwater resources. This project evaluated a unique, previously untested, type of soil organic amendment, that is, coarse wood chips, for capturing and storing scarce precipitation and improving desertified, sandy soils. A field plot experiment was conducted in Ningxia, China, from 2011 through 2016, comparing unamended sandy soils with three coarse woody amendments, including (a) surface‐applied mulch, (b) wood chips incorporated into the top 20 cm of soil, and 3) incorporated wood chips combined with a branch lattice shelter over the soil surface—all treatments replicated under both irrigated and nonirrigated conditions. Precipitation patterns and soil moisture content were compared between 2012 and 2015, and related soil physical and chemical properties were monitored continuously, as well as alfalfa yields in 2015 and 2016. Results indicated that amended soils maintained significantly higher soil water contents between rain events, decreased the number of days below the permanent wilting point, and improved soil properties and alfalfa growth. The combination treatment of wood chips and a branch shelter performed the best among treatments, exhibiting increases in average water storage 50% or more above controls. Unlike highly degradable soil amendments, the slow decomposition of the coarse wood chips resulted in continuous benefits for all 5 years. This use of coarse wood chips represents a timely new addition to the toolbox of soil amendments, providing a mechanism for immediate, long‐lasting restoration of the world's degraded and desertified soils that will foster global food and water security. 相似文献
404.
Tian Cai Charles Steinfield Hastings Chiwasa Tadala Ganunga 《Land Degradation u0026amp; Development》2019,30(11):1336-1344
Soil and land degradation is a common issue in Sub‐Saharan Africa leading to poor yield and threatening food security, yet soil conservation technologies remain underutilized. To build on prior work that primarily emphasizes demographic differences in adoption, this study contributes by identifying underlying social and cultural factors that influence farmers' perceptions about and willingness to adopt soil conservation management practices in a rural region of Malawi. Key informant interviews were first conducted to identify constraints slowing composting adoption, which were then used to structure the creation of participatory videos—videos created with the active participation of local farmers that demonstrated compost manure practices and benefits. Farmers from the same communities subsequently participated in focus group discussions before and after the moderated screening and discussion of these videos in order to obtain a more in‐depth understanding of the constraints and possible ways to overcome them. Among the identified constraints to the use of composting were inefficient government programs such as the Farm Input Subsidy Program that contributed to a belief that only subsidized chemical fertilizers provided positive returns on investment, a lack of support from extension services that diminished compost use, social norms around gender that hindered women farmers from attempting to use composting, and livelihood strategy changes that led to labour shortages. Findings from the focus groups showed that the participatory video method encouraged adoption by helping farmers, and especially women, to reconsider composting, test it, and reflect upon social and cultural constraints impeding adoption. Over half of the farmers in the study tested composting for the first time after discussing the videos and changed their perception of both the value of composting and their own ability to use these types of soil conservation practices. 相似文献
405.
Sophie C. Sherriff John S. Rowan Owen Fenton Phil Jordan Daire
hUallachin 《Land Degradation u0026amp; Development》2019,30(18):2257-2271
Agricultural land, and arable farming in particular, is commonly associated with increased soil erosion risk. Such systems are most vulnerable during low groundcover periods, but downstream delivery is ultimately controlled by connectivity. This study provides a catchment‐scale sediment budget integrating three discrete but complementary investigations spanning different temporal and spatial scales. The first gives details on suspended sediment fluxes at the catchment outlet (2009–2012). The second provenances sources of fluxes using quantitative sediment fingerprinting. The third sets recent data in a multidecadal (60‐year) context using radiometric (137Cs) field‐scale soil loss estimates. The catchment observatory (11 km2) is low relief with predominantly well‐drained soils and dominated by spring‐sown cereal cropping through the study period. Modelling 137Cs inventory losses across 30 fields provided a catchment‐wide mean soil loss of 2.0 Mg ha−1 yr−1. Although such rates are not atypical of intensively managed agriculture across Europe, they are considerably higher than contemporary sediment export yields of 0.12 Mg ha−1 yr−1 of which fingerprinting revealed that contemporary slope erosion contributed less than 25% (0.03 Mg ha−1 yr−1). No evidence of floodplain or in‐channel sediment storage was consistent with disconnectivity. Instead, it is hypothesised that soil loss is associated with coextraction from root crop harvesting of previously widespread sugar beet crops. Considering that the highest mass‐specific 137Cs concentration occurred during the 1960s, there appears to have been significant depletion of the cumulative 137Cs inventory where root crop harvesting occurred as compared with atmospheric fallout ‘reference sites.' The study highlights the value of multiple methodologies when seeking to understand legacy issues within agricultural catchment settings. 相似文献
406.
Xiao‐hong Jia Yuan‐shou Li Bo Wu Qi Lu Xin‐rong Li 《Land Degradation u0026amp; Development》2019,30(18):2197-2210
Soil organic carbon (OC) and nitrogen (N) associated with particle size fractions can be used as sensitive indicators to evaluate impacts of land use change on soil total OC (TOC) and total N (TN) pools. Aeolian sandy‐soils were collected from seven sites in the Tengger Desert, representing a 56‐year chronosequence of plant restoration at decadal intervals in an arid desert region. Bulk soils were separated into silt + clay (<53 μm), fine sand (53–100 μm), and coarse sand (>100 μm) fractions. TOC and TN concentrations of bulk soil and their levels associated with particle size fractions were analyzed. Results showed that plant restoration promoted C and N sequestration in both topsoil and subsoil layers over time, as indicated by elevated levels of OC and N associated with silt + clay and sand fractions. TOC and TN concentrations of 56‐year restored topsoil respectively increased by 31‐ and 43‐fold than did the control (moving dunes); corresponding levels associated with silt + clay or coarse sand fraction respectively increased by more than 30‐ and 20‐fold, whereas less than 15‐fold increases were found in fine sand fraction. In the early stages of plant restoration, both C and N sequestration primarily resulted from finer particle size fractions. In the later stages, increased C sequestration was principally derived from coarse sand fraction, whereas N sequestration was mainly derived from silt + clay fraction. The results highlight that plant restoration stage and soil textural change are key factors leading to divergent soil C and N sequestration in the arid desert region. 相似文献
407.
408.
The bamboo vinegar was used to produce organic calcium,and different concentrations of NaCl,CaCb and organic calcium solutions as deicer were sprayed evenly on the potted Cymbidium ensifoiium and collected soil, and the growth of C.ensifoiium was observed everyday,and the physical and chemical properties of soil were analyzed.The results indicate that all the 3 types of salt solutions had certain influence on C.ensifolium,while the organic calcium had less effect on C.ensifolium than NaCl and CaCl2,and both of NaCl and CaCl2 had little effect on the pH of soil while organic calcium increased greatly the pH of soil,and the organic matter and cationic exchange capacity of soil reduced,and the content of total N, P in soil also reduced while the apparent content of total K in soil increased.By above comparison,the effect of organic calcium made by bamboo vinegar on C.ensifolium and soil was less than that of NaCl and CaCl2,in addition smaller the concentration of salt solution was,less the effect of salt solution on C.ensifoliumand soil was. 相似文献
409.
《Scandinavian Journal of Forest Research》2012,27(1-4):145-152
Repeated analyses of exchangeable K, Ca, Mg and Zn revealed that the pools have decreased significantly in the topsoil (0–5 cm) of south Swedish beech forest during the 1980s. The largest decreases of K, Ca and Mg were found in the originally least acid soils, indicating that the limit for further losses from the topsoil is being approached in the most acid soils at today's deposition climate. The decrease of Zn was, on the other hand, largest in the most acid soils. Manganese had increased in especially the least acid soils, probably due to a conversion from non‐exchangeable pools as a result of the acidity change. The base saturation of the studied beech stands ranged 7.7–58.5% (mean 20.3%). The decrease rate of the exchangeable pools of K, Ca and Mg, estimated from two different time series has been relatively constant since 1949. The Zn pool has, however, decreased faster during the last decade, partly due to a lowered deposition of this element. Extrapolation of the data indicates that, as an average, only 20% of the pools of 1950 will remain in the topsoil in the year 2050. 相似文献
410.
《Communications in Soil Science and Plant Analysis》2012,43(11):1512-1522
A correct determination of nitrogen (N) fertilization thresholds in wheat that is based on objective yield produces efficient use of this nutrient. Nitrogen fertilization recommendations for traditional wheat require determination of nitrate (NO3 ?)-N availability at 60 cm deep at planting time. However, this methodology is complicated, expensive, and time-consuming; thus, the determination of NO3 ?-N level at a lesser depth and at a different time would be desirable. The goals of this work were to determine available N in soil thresholds for traditional and French germplasm wheats and the feasibility of diagnosing N requirements by measuring NO3 ?-N at 40 cm deep, at planting or tillering times, in the southeastern Pampas. The experiments were factorial combinations of N rates and fertilization times (planting and tillering) at different sites and years during 2002–2006. Nitrogen fertilization significantly increased grain yield and protein content. French varieties presented greater grain yield (23%), lower protein content (11%), and greater yield per N unit, indicating greater N-use efficiency (NUE) than traditional varieties. A similar relationship was determined between grain yield and available N at both sampling depths. This might be explained by the strong association between NO3 ?-N content at 60 and 40 cm deep at both sampling dates. Maximum yield and available N determined at 60 or 40 cm soil deep showed that thresholds were lower for tillering than for planting, regardless of the genotype (152 and 174 kg of available N, respectively). Available N thresholds for 95% of maximum yield were less at 0–40 cm deep than at 0–60 cm deep (10 and 14 kg N ha?1 for traditional and French genotypes, respectively). The results of this experiment suggest the possibility of diagnosing N requirements for wheat by measuring NO3 ?-N content at 40 cm deep, instead of the usual 60 cm, for both traditional and French genotypes. 相似文献