Tobacco production and curing is the single most important contributor to soil degradation and deforestation. To minimise the environmental effects of tobacco production, the environmentally friendly, and energy-efficient rocket barns technology was developed. In spite of its energy saving and environmental benefits, the adoption of rocket barns remains low and understudied. This paper assessed farmers perception and factors affecting the adoption of rocket barn technology. Data was collected using in a cross-sectional survey using structured questionnaires were from 242 Flue Cured Virginia (FCV) tobacco farmers in Uganda. Analysed was done using SPSS and STATA software. Results show that the adoption of rocket barn technology was low, at 12%, with farmers. Farmers perceived adopting the rocket barns technology to be risky and costly. Experience, training, distance to wood fuel, access to extension information, and benefits and risk perceptions were the major determinants of adoption of rocket barns technology. Promotion and adoption of rocket barns technology will require concerted sensitization and training of farmers on the environmental benefits of rocket barn technology. Emphasis such efforts should target the relatively young and inexperienced FCV tobacco farmers.
Tidal marsh wetlands in the Yellow River Delta provide valuable eco-services to the local population and global ecology. However, this area is suffering from serious degradation under the stresses of social development and climate change. Hydrological connectivity, a new framework in hydrology and ecology, has been proposed as the main factor affecting the ecological processes in coastal wetlands; however, its role in hydrology–soil–vegetation interactions remains unclear. In this study, the researchers parametrically quantified the hydrological connectivity in the tidal marsh wetlands and analyzed its relationship with Phragmites australis, one of the dominant species in this area. Our results showed threshold-like effects on the interaction between hydrological connectivity and P. australis on the plot scale. When biomass is lower than 2.2 kg/m2, the population density and structure size were found to increase with hydrological connectivity. When the biomass is higher than the threshold, the plots disconnected hydrologically because of high water consumption. Compared with soil chemistry, salinity, and water soil content, hydrological connectivity in the surface soil layer is more strongly linked to the plant traits and spatial structure in the tidal marsh wetlands due to the narrow ranges of other variables. Based on the authors’ analysis, the researchers do not recommend dense plantation of P. australis, especially near the freshwater sources in the tidal marsh, because of its high reproduction ability and competitive nature, which may cut the freshwater connectivity off, lowering the richness of plant species and habitat diversity.
We established three simulated erosion severities with topsoil depths of 10, 20 and 30 cm in a Mollisol farmland under a maize-soybean rotation system with no-tillage. After three consecutive years of field experiment, the decrease in topsoil thickness from 30 to 10 cm resulted in 9−22% of decrease in maize yield but not soybean. Compared to the 30 and 20-cm topsoil thickness, the 10-cm topsoil significantly lowered root and shoot biomass of maize at the jointing (V7) and milk stages (R3) and of soybean at the mid-seed filling stage (R6). Compared to the 30-cm topsoil, the 10-cm topsoil decreased available nitrogen and phosphorus in soil by 42% and 36% under maize, and by 25% and 19% under soybean, respectively, while the shallow topsoil also decreased N, P and K uptake per unit root length with the decreases being less for maize than soybean. Compared to the 30-cm topsoil, the 10-cm and 20-cm topsoil significantly increased the activities of urease, phosphatase and invertase in maize-grown soil, but not in soybean-grown soil except for the activity of urease in 10-cm topsoil. Maize was more sensitive to soil erosion than soybean due to the greater decreases in soil nutrient availability and its capability of nutrient uptake. The greater stimulation of nutrient mineralization processes in soil did not alleviate the nutrient constraint to maize yield under severe erosion conditions.
Insect herbivore has great impacts on biogeochemical cycling in forest ecosystem, but experimental tests on the herbivory-decomposability relationship at the inter-specific level are rare. We conducted a 400-day field decomposition experiment in a temperate mixed deciduous forest and measured mass remaining rate, decomposition constant, total loss of carbon (C) and nitrogen (N) of litter leaf with/without obvious damage by chewing insects for different tree species. We found that herbivory effect on initial litter quality (C: N ratio) varied with species, showing a markedly negative effect on M. alba (-5.78%) and positive effect on Q. acutissima (+5.35%). Herbivory damage increased decomposition constant for M. alba and L. formosana with higher special leaf area, but decreased it for D. kaki and Q. acutissima with lower special leaf area. The contrasting effects of insect herbivory on litter decomposition could be attributed to the variability of litter initial quality caused by herbivory. Our finding that herbivore damage showed inter-specific variability in both litter quality and decomposition rate suggests that herbivory induced feedbacks to nutrient cycling and ecosystem function should be estimated at the species level in multi-species mixed deciduous forest.
The black soil region of northeast China is one of the most productive regions of the world. The depth of A horizon is rapidly decreasing due to excessive erosion. A strategy for erosion hazard evaluation and soil conservation planning has been proposed and tested on the region. Climate, geomorphology, DEM, soil, landuse, runoff plot and corn yield data were compiled. Soil erosion rate, A horizon thickness and corn yield under six conservation scenarios during 2020~2200 was predicted. The six scenarios include Present (continue present practices), Contour (contour tillage), Straw (straw incorporated in tillage layer), Combo 1 (contour tillage and terracing etc.), No-till (no-till farming) and Combo 2 (partially Combo 1 and partially No-till). Current soil life expectancy of A horizon (SLEA), which is the time until a critical horizon thickness needed for sustaining crop production is reached, was calculated for each scenario. Erosion hazard degrees were determined with SLEA. Croplands with SLEA of <0 a, 0 a~20 a, 20 a~100 a, 100 a~1000 a and ≥1000 a, were classified as “Damaged”, “High hazard”, “Moderate hazard”, “Low hazard” and “No hazard”, respectively. Current area ratio of “Damaged” and “High hazard” and “Moderate hazard” was found to be 8%, 5%, and 22%, respectively. The optimum conservation practice was found to be No-till for “Damaged”, “Combo 2” for “High hazard”, “Moderate hazard” and “Low hazard” and Present for “No hazard”. An optimum conservation schedule was also suggested for each township to maintain all soils to have an A horizon above 20 cm.
The overarching goal of this study is to test innovative monitoring strategies for agricultural properties at watershed towards effectively locating erosions and correcting them, through the implementation of changes in soil management strategies. The purpose is to recover and restore degraded areas, and promote conservation agriculture. The results are, assessed by remote sensing and water quality indicators. In 2019, twelve years were completed of inspection/monitoring at Rio do Peixe watershed. From 2007 to 2017, 14,076 ha, were inspected at Vera Cruz sector, using the Conventional CDA methodology, with 94 properties having been notified. In Ocauçu, a total of 82 properties were notified, in a total surface of 9,027 ha. In Marília, the Innovative CDA Methodology was used, which allowed the inspection and rehabilitation of 52 properties, across 27,775 ha, from 2017 to 2018. After the notifications, the owners presented the conservationist technical projects for each property, which were, implemented using conservation practices, such as: improvement of vegetation cover and crop rotation, to control laminar erosion; and agricultural terracing, divergent channels and containment basin, to control gullies erosions. This work promoted a transformation from degrading agriculture to conservation agriculture, with degraded pastures having been altered into agricultural areas, with the implementation of the No-tillage. Pastures were recovered through the Integrated Crop-Livestock System, and occupancy rate was increased by 31%. This work has demonstrated to benefit Watershed farmers, by increasing their productivity and consequently the profit, as well as the local communities, improving the quality of water that supplies the region.
Little information is available about the effects of different species of shrubs on the composition of the soil seed bank (SSB) in semiarid regions. We determined the role of three dominant shrub species on SSB characteristics and evaluated their potential for their possible use in rangeland restoration projects. Fifteen sites, each containing three shrub species (Amygdalus scoparia, Daphne mezereum and Ebenus stellata) and a herbaceous patch (control) in close proximity, were sampled and their SSB density, species richness and diversity at 0-10 cm depth were determined. The results showed that the density of the SSB was highest under A. scoparia (1133 seeds per m2) and lowest in herbaceous vegetation (110 seeds per m2). Species richness and diversity of the SSB was significantly greater under E. stellata than under the other shrubs and control. This study revealed that the extent to which vegetation affected SSB characteristics did not only depend on the presence of shrubs, but also on the species of shrub. These different roles of different species of shrubs on SSB are advised to be considered in the restoration of degraded areas through planting of shrubs in semiarid regions. Planting and the extension of E. stellata cover in degraded sites could be of priority due to its prominent role in herbaceous SSB reservoir and species diversity and richness.
Land serves as a vital production resource, and therefore, land planning plays an important role in sustainable land-use design. Increasing the global population alters landscapes via land-use and land-cover change across different landscapes, including the drylands. Iran includes large areas of dryland, where the population increased by 60% from 1985 to 2016. Further population increase in Iran would require more land resources to be allocated for human needs. However, the pace and patterns of these changes remain unclear. The aim of this study was to map land-cover change from 1985 to 2016 and predict future land-cover change in the Zayandehrood ecologic sub-basins of Central Iran. By using multiseasonal Landsat imagery, nine thematic classes were mapped with a random forest classifier for 1985, 1998, and 2016 with an overall accuracy of 80% for each period. Classification results revealed that from 1985 to 2016 residential areas doubled and industrial areas increased at the expense of rangelands. Our study also revealed cropland expansion at the expense of rangelands, cropland abandonment and contraction of croplands due to residential and industrial development. Prediction of changes by 2036 with a multi-layer perceptron neural network and Markov chain analysis revealed further expansion of industries and residencies particularly nearby the protected areas such as Ghamashlu Wildlife Refuge. Predicted contraction of some degraded agricultural lands and concomitant agricultural expansion in the agricultural frontier by 2036, underscore the importance of sustainable land management in highly arid areas of Iran and improvement of the strategies for the protection of rangelands.
Globally, temperate grasslands have been significantly altered and subsequently degraded as a result of increased human population, urbanisation, and agriculture. Weeds now dominate most of these ecosystems, resulting in the loss of ecosystem services, reduced carrying capacity for farmers, and loss of habitat for native animals. This paper reviews the literature of temperate grassland restoration efforts from across the globe, and observes what techniques and combinations have been used successfully and unsuccessfully to reduce weed dominance and promote native recruitment and establishment. The findings of this review clarify that weed management should be ongoing in all projects, while optimal revegetation methods and grazing regimes are specific to site location and study scope. There is a need for an increase in long-term monitoring of restoration projects in order to make assumptions with greater confidence.
The effects of forest conversion from natural forest to agricultural system on soil microbial composition still need further study. Especially, impact on soil function after forest conversion is not yet known. In this study, by using metagenomic sequencing as well as 16S and ITS sequencing technology, we evaluated the soil microbial composition, diversity and functions based on a large number of soil samples of tropical rainforest and rubber plantation across the whole island of Hainan, south China. The results showed that (1) forest conversion changed microbial composition from bacterial groups of Proteobacteria to Chloroflexi, and fungal groups from Basidiomycota to Ascomycota. (2) The bacterial alpha diversity, beta diversity as well as the total diversity did not decrease after forest conversion. However, beta diversity of fungal community reduced resulting a net loss of total OTU richness. (3) There was no difference in soil functional compositions and diversity between rubber plantations and rainforest, however, the relative gene abundance of most COG functions, KEGG functions, CAZy functions as well as Antibiotic gene were significantly different between rubber plantation and tropical rainforest. (4) Soil pH and environmental heterogeneity were the main driver for microbial taxonomic composition and gene functional composition. Land use did not result in changes of functional gene composition, but the relative abundance of functional gene. The changed relative abundance gene would alter the ecosystem processes. In conclusion, our results confirmed that land use changes alter the soil microbial community structure and can have profound effects on ecosystem functions and processes.
Land use and coverage surveys show that 30.5% of Brazil´s territory was dedicated to the production of food, fibers, biofuels and raw materials. This paper fulfils a gap and provides information to society and decision-makers about the effectiveness of the adoption of Conservation Agriculture (CA) principles with Zero Tillage (ZT/CA) and integrated Crop-Livestock-Forest (iCLF-CA) systems as the central policies to mitigate soil erosion, the main agent of land degradation and productivity loss. The increase in CA area by 2030 was estimated using Holt’s damped for ZT/CA and simple linear models for iCLF-CA. The annual potential for soil erosion with intensive conventional tillage and monocropping, considering land use and cover in 2017, is of 3.0 billion tonnes. The economic impact, based only on replacement of nutrient losses, is estimated to be 15.7 billion US$ per year. To control soil erosion by water, to intensify agricultural production and mitigate the greenhouse gas emissions are the goals of the PronaSolos, a national program for detailed soil survey and interpretation. The annual economic impact of the adoption of CA principles by controlling soil erosion were estimated as at 1.5 billion US$ for ZT/CA in 2017 and 0.5 billion US$ for iCLF-CA in 2015. The future increase of the CA area was forecast at 34.4 Mha and 25.4 Mha for ZT/CA and iCLF-CA, respectively. The positive impacts of the adoption of CA principles in Brazil are the result of the determination of farmers, among many actors, and of the effectiveness of government plans and policies.
Soil resources in East Africa are being rapidly depleted by erosion, threatening food-, water- and livelihood security in the region. Here we demonstrate how integration of evidence from natural and social sciences has supported community-led change in land management in an agro-pastoral community in northern Tanzania impacted by soil erosion. Drone survey data and geospatial analysis of erosion extent and risk, supported by communication of ‘process’ and ‘structural’ hydrological connectivity, was integrated with local environmental knowledge within participatory community workshops. Rill density data were compared between cultivated plots that had been converted from pastoral land recently and more established plots where slow-forming terrace boundaries were more established. Slope length and connectivity between plots were key factors in development of rill networks. At the two extremes, recently converted land had a rill density ca 14 times greater than equivalent established slow forming terraces. Direction of cultivation, regardless of plot boundary orientation with contours, also enhanced rill development. Evidence of this critical time window of hillslope-scale rill erosion risk during early phases of slow-forming terrace development successfully underpinned and catalysed a community-led tree planting and grass seed sowing programme to mitigate soil erosion by water. This was grounded in an implicit community understanding of the need for effective governance mechanisms at both community and District levels, to enable community-led actions to be implemented effectively. The study demonstrates the wide-reaching impact of integrated and interdisciplinary ‘upslope-downslope’ thinking to tackle global soil erosion challenges.
The native and invasive species in the Yellow River Delta were examined for their spatiotemporal characteristics and succession pattern. First, the appropriate Sentinel-2 and Landsat-8 images from 2018 were selected according to phenological characteristics. A random forest algorithm was used to verify the image spectral band significance and separability using selected images to determine the native and invasive species. Then, the spatiotemporal variation of habitat structure of native and invasive species is discussed in depth from the perspective of landscape ecology. Finally, the expansion direction and expansion mode of S. alterniflora were further analyzed, and main results were obtained as follows. (1) At the medium-high resolution multi-spectral image level, the accuracy of different vegetation community extractions can be improved by taking into consideration both the vegetation phenology and the spectral features of remote sensing images. (2) Sentinel-2 images with red edge bands have obvious advantages in vegetation community extraction as compared to Landsat-8 images (Sentinel-2, OA=82.86%, Kappa coefficient=0.79; Landsat-8, OA=78.77%, Kappa coefficient=0.74). (3) The expansion pattern of the S. alterniflora community became spatially continuous, more regularized and aggregated overtime. (4) The expansion in the north shore mainly faces to the sea, and the south bank mainly faces to the land, and this phenomena is closely related to the sedimentation of the Yellow River Delta. Marginal and external expansion both occurred, but marginal expansion predominated. The results from this study have important theoretical and scientific value for the environmental protection and sustainable development of the entire Yellow River Delta.
This article seeks to analyze relevant federal public policies in Brazil related to soil and water conservation in order to extract the key lessons learned upon its implementation to support the participatory formulation of the National Plan for Soil and Water Sustainable Management. The policy analysis was made based on six strategic axis: Legislation, Prevention, Conservation, Recovery, Monitoring and Integration. These analyzes results aim to contribute to subsidize the Plan construction and identify instruments to increase the use of soil and water resources efficiency in agricultural production according to the different environmental, social and economic conditions of the country’s regions. Seven public policies were selected, characterized and analyzed. The results showed that none of the analyzed public policies are taking enough actions to accomplish with the six strategic axis for soil and water sustainability. These gaps were detected and described as opportunities to be considered under the new national policy framework. The needs for greater involvement of civil society and other relevant stakeholders on policy design and decision making as well as integration among federal ministries were also identified. In conclusion, it is suggested that the new Plan should be designed under a decentralized and participatory process to effectively gather engagement and stronger commitment from governments and other strategic stakeholders in public decisions towards soil and water sustainable management in the agriculture, thus contributing to sustainable rural development.
The Tibetan Plateau, a vulnerable eco-region for global warming, has huge value of science and practice on ecological restoration to mitigate and adapt to climate change. Sophora moorcroftiana shrubs, which are widely distributed in the middle reaches of Yarlung Zangbo River basin, have been recovered on desertified land benefiting from natural restoration during the past decades. However, the effects of habitat conditions in different topographies on population structure and distribution of S. moorcroftiana have been rarely reported. Here, we achieve the variation of vegetation and micro-topography of S. moorcroftiana population by a series of field surveys with Terrestrial Laser Scanning (TLS) during natural restoration in 2017. The results indicate that the positive correlation between height and CPA reached the 99% confidence level (p < 0.01). The plant height was significantly correlated with the elevation and slope (r = 0.167 and 0.145, respectively; p < 0.01). While the distribution of S. moorcroftiana population decreased along increasing elevation, and the trend of distribution was decreasing firstly, increasing secondly and decreasing finally with increasing slope. The habitat conditions on the southwest slope of approximately 20°-25° with altitudes of 3593-3643 m most favor to the distribution of S. moorcroftiana population in this region. These will help to understand the effect of micro-topography on population structure and distribution of Sophora moorcroftiana in southern Tibetan Plateau and assess the effectiveness of natural restoration of Sophora moorcroftiana in different topographies.
We use recent plot-level panel data from Tanzanian smallholder farmers to investigate maize yield responses to inorganic fertilizer under variable soil carbon conditions. Unlike many prior studies which consider total carbon measurements, we focus on active soil carbon, which is the component that most influences key soil functions, such as nutrient cycling and availability. Active soil organic carbon is found to strongly influence maize yield response to nitrogen fertilizer. These results highlight important sources of variation in the returns to fertilizer investments across plots and smallholder farmers in the region. When farmgate prices for maize and fertilizer are incorporated into calculations of economic returns, we find that the profitability of fertilizer use is strongly dependent upon farmgate price ratio assumptions: under our most optimistic agronomic response estimates, 71% of farmer plots have an average value-cost ratio (AVCR) greater than 1.5 at a maize-nitrogen price ratio of 0.15. That share drops to 30% at a price ratio of 0.12 and 2% at a price ratio of 0.09. Our findings provide insights into the intertwined biophysical and economic underpinnings of low levels of fertilizer use in Tanzania and elsewhere in the region. Raising active carbon stocks in smallholder systems may be a strategic priority in many areas for incentivizing greater use of inorganic fertilizer, reversing land degradation, and achieving sustainable agricultural intensification.
How soil quality and microbial communities change in conjunction with stand age in plantations is poorly understood. Here, we evaluated soil quality by using an integrated soil quality index (SQI) and traced the paralleled shifts in fungal community composition by high-throughput sequencing in a chronosequence of Chinese fir (Cunninghamia lanceolata) plantations (stand age of 3, 16, 25, 32, >80 years). Soil properties showed pronounced changes with stand age in the top 0-5 cm. The most prominent increase from 3 to >80-year-old stand was for soil organic carbon (SOC, by 2.1-times), total nitrogen (TN, 1.9-times) and available phosphorus (AP, 2.2-times). SQI increased logarithmically with stand age, with sharper change seen in the 0-5 cm layer than in the 5-15 cm layer. Mycorrhizal fungi increased in abundance initially in younger stands, but then they were gradually replaced by saprotrophic fungi in older stands due to the increase in litter input, which sustains saprotrophs. The positive correlation between saprotrophic fungi and the key soil quality indicators, such as TN, AP and NH4+, showed that higher soil quality was tightly linked with the enrichment of decomposers. Mycorrhizal taxa, such as orders Sebacinales, Thelephorales and Russulales, were positively correlated with acid phosphatase mobilizing P from organic matter. This suggests that the establishment of mycorrhizal fungi sustains tree productivity in younger stands under low soil quality. We conclude that the increase in soil quality throughout the development of Chinese fir plantations is closely linked with the observed transition of fungal communities from mycorrhizae to saprotrophs.
Conservation agriculture (CA) systems represent a set of three soil management principles that include minimal soil disturbance, permanent soil cover and crop rotations whereas the CA-based systems in this study add the bed and furrow tillage structures as integral elements of CA. This study aimed at investigating the long-term (2005-2013) influence of CA-based systems on soil health and crop productivity in northern Ethiopia. The treatments include two types of CA-based systems (permanent raised bed PRB and contour furrowing CF) and conventional tillage (CT). The experimental layout was arranged in a randomized complete block design. Soil samples were collected at 0-10 cm soil depth to assess soil health. Wheat root samples were used to measure arbuscular mycorrhizal fungi (AMF) colonization percentage using grid line intersect method. Piecewise structural equation modeling (PSEM) was used to understand linkages between management practices, soil health and crop productivity. Higher soil microbial biomass carbon (SMBC), AMF spore abundance and root colonization were recorded in PRB followed by CF as compared to CT (P < 0.05). Carbon sequestration rate, nutrient availability, plant available water capacity and air capacity were significantly higher in PRB and CF compared to CT. Outputs of the PSEM highlighted two pathways in which CA-based systems contributed to improved productivity: (1) via higher density of bacteria and improved hydraulic conductivity, and (2) via higher density of fungi and increase soil organic carbon content in the topsoil. The study concludes that CA-based systems have the potential to improve crop productivity through improved soil health.