Adjacent Farmland Research Articles

Geoinformation modelling of forest shelterbelts effect on pecuniary valuation of adjacent farmlands

The paper highlights the research results of ecological and economic role of lands under forest shelterbelts within agricultural landscapes. The achieved results have enabled to state that such plantations are the major focus towards agriculture enhancement. It has been ascertained the effective melioration impact of forest shelterbelts on the adjacent areas within different climatic regions and that the field-protective forestation has a common positive trend. On the other hand, some differences in observation results of forest shelterbelts research can take place due to unequal geographical and climatic conditions.

Geoinformation modelling of forest shelterbelts effect on pecuniary valuation of adjacent farmlands

Geoinformation modelling of forest shelterbelts effect on pecuniary valuation of adjacent farmlands

Impacts of grassland management on wader nest predation rates in adjacent nature reserves

Wetlands have undergone significant loss and degradation over the past century, primarily through agricultural development. In the UK, wet grassland habitats support important breeding wader populations, but agricultural intensification has led to severe population declines. Management on nature reserves can be successful at attracting breeding waders, but productivity has been limited by the impacts of generalist predators of nests and chicks in these relatively small areas. Targeting agri-environment management to form buffer zones around reserves has been proposed as a potential strategy to improve landscape connectivity. However, the implications of such strategies for predator movement and activity are unknown. Here we assess whether predation rates of wader nests and predator activity within and across a wet grassland reserve are influenced by whether adjacent farmland is under agri-environment scheme (AES) management for breeding waders. In fields adjacent to AES-managed land, fox activity was higher and nest predation rates remained constant with increasing distance from the reserve edge into the reserve. Conversely, fox activity and wader nest predation rates were lower in fields close to the reserve edge and adjacent to commercial land, and increased with distance from the reserve edge although only to levels seen elsewhere on the reserve. This suggests that predators concentrate activity away from commercial farmland, and that the consequences for nest predation of deploying AES around nature reserves will likely depend on the extent to which they attract breeding waders and the strength of any consequent density-dependent effects on predation rates.

Distribution of antibiotic resistance genes (ARGs) in anaerobic digestion and land application of swine wastewater

Swine farm and the adjacent farmland are hot spots of ARGs. However, few studies have investigated the on-site occurrence of ARGs distributed in the process of anaerobic digestion (AD) followed by land application of swine wastewater. Two typical swine farms, in southern and northern China respectively, with AD along with land application were explored on ARG distributions. ARGs were highly abundant in raw swine wastewater, AD effectively reduced the copy number of all detected ARGs (0.21–1.34 logs removal), but the relative abundance with different resistance mechanisms showed distinctive variation trends. The reduction efficiency of ARGs was improved by stable operational temperature and longer solid retention time (SRT) of AD. ARGs in soil characterized the contamination from the irrigation of the digested liquor. The total ARGs quantity in soil fell down by 1.66 logs in idle period of winter compared to application period of summer in the northern region, whereas the total amount was steady with whole-year application in south. Some persistent (sul1 and sul2) and elevated ARGs (tetG and ereA) in AD and land application need more attention.

Trends of deposition fluxes and loadings of sulfur dioxide and nitrogen oxides in the artificial Three Northern Regions Shelter Forest across northern China

This study provides the first estimate of dry deposition fluxes of criteria air pollutants (SO2 and NOx) across the Three Northern Regions Shelter Forest (TNRSF) region in Northern China and their long-term trends from 1982 to 2010 using the inferential method. Dry deposition velocities of SO2 and NOx increased in many places of the TNRSF up to 118.2% for SO2 and 112.1% for NOx over the last three decades due to the increased vegetation coverage over the TNRSF. The highest atmospheric deposition fluxes of SO2 and NOx were found in the Central-North China region, followed by the Northeast and the Northwest China regions of the TNRSF. A total of 820,000 t SO2 and 218,000 t NOx was estimated to be removed from the atmosphere through dry deposition process over the TNRSF from 1982 to 2010. About 50% of the total removal occurred in the Central-North China region. The estimated total SO2 and NOx dry deposition fluxes from 1982 to 2010 between a TNRSF site in this region and an adjacent farmland outside the TNRSF showed that the fluxes of these two chemicals at the TNRSF site were the factors of 2–3 greater than their fluxes in the farmland.

Shifts in Abundance and Diversity of Soil Ammonia-Oxidizing Bacteria and Archaea Associated with Land Restoration in a Semi-Arid Ecosystem.

The Grain to Green Project (GGP) is an unprecedented land restoration action in China. The project converted large areas (ca 10 million ha) of steep-sloped/degraded farmland and barren land into forest and grassland resulting in ecological benefits such as a reduction in severe soil erosion. It may also affect soil microorganisms involved in ammonia oxidization, which is a key step in the global nitrogen cycle. The methods for restoration that are typically adopted in semi-arid regions include abandoning farmland and growing drought tolerant grass (Lolium perenne L.) or shrubs (Caragana korshinskii Kom.). In the present study, the effects of these methods on the abundance and diversity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were evaluated via quantitative real-time PCR, terminal restriction fragment length polymorphism and clone library analysis of amoA genes. Comparisons were made between soil samples from three restored lands and the adjacent farmland in Inner Mongolia. Both the abundance and community composition of AOB were significantly different between the restored lands and the adjacent control. Significantly lower nitrification activity was observed for the restored land. Clone library analysis revealed that all AOB amoA gene sequences were affiliated with Nitrosospira. Abundance of the populations that were associated with Nitrosospira sp. Nv6 which had possibly adapted to high concentrations of inorganic nitrogen, decreased on the restored land. Only a slight difference in the AOB communities was observed between the restored land with and without the shrub (Caragana korshinskii Kom.). A minor effect of land restoration on AOA was observed. In summary, land restoration negatively affected the abundance of AOB and soil nitrification activities, suggesting the potential role of GGP in the leaching of nitrates, and in the emission of N2O in related terrestrial ecosystems.

서식지 적합성 평가를 이용한 수변지역 핵심 보전지역 선정 - 수달을 대상으로 -

In Korea, significant riparian areas have been developed due to river maintenance projects. Introduction of new riparian facilities can negatively affect wildlife in the riparian areas. This study focuses on selecting core conservation areas for Eurasian Otter(Lutra lutra) to support decision making process for development of riparian areas. For the study, first of all, field data of study site were collected by field surveys. Secondly, stream naturalness was assessed to understand physical environments of the study sites. Thirdly, habitat suitability was assessed using occurrence data of Eurasian Otter and environmental data. Lastly, core areas for conservation was selected by comparing and synthesizing stream naturalness map and habitat suitability map. The selected core areas showed several characteristics. The number of artificial facilities is low in the core areas. Rocks which are preferred by Eurasian Otter to eat and excrete are plentiful in the core areas. Also, the ratio of adjacent farmland is high. Based on the analyses, it is expected that this study can contribute to decision making process for environmental spatial plans to better conserve habitats of Eurasian Otter.

Impacts of farmland conversion to apple (Malus domestica) orchard on soil organic carbon stocks and enzyme activities in a semiarid loess region

AbstractLand‐use change often affects the sizes of soil organic carbon (SOC) stocks and the activities of soil enzymes. Responses of relevant soil quality indices caused by farmland conversion to orchard are largely unknown in the semiarid loess regions. This study was conducted at orchard sites, which have been under very intensive cultivation, to evaluate the impacts of farmland conversion to apple (Malus domestica) orchard on SOC stocks and soil enzyme activities in the semiarid loess region of Weibei, Shaanxi province, China. The spatial and temporal changes in a variety of soil quality indices were measured for the 0–100 cm soil profile in apple orchards of three age groups (< 10 y, juvenile; 10–15 y, mature; > 15 y, over‐mature) and adjacent farmlands (control). After farmland conversion, total SOC (TOC) content and density and soil alkaline phosphatase activity significantly decreased, while soil catalase activity increased for the 0–100 cm soil profile. The labile SOC (LOC) content, its proportion to TOC content, and carbon management index (CMI, changes in the total content and lability of SOC) significantly increased in the 0–40 cm soil layer, whereas soil urease and invertase activities only increased in the 0–20 cm layer (P < 0.05). With increasing age of apple orchards, SOC stocks significantly increased after 10 y, being more than 10% larger in mature and over mature orchards than in adjacent farmlands. The LOC content and CMI value also had an increasing trend, while soil enzyme activities showed different response patterns. There were significant correlations between soil enzyme activities, SOC fractions, and CMI value (P < 0.05). We concluded that farmland conversion to apple orchard affected soil quality by reducing SOC stocks in the soil profile and changing SOC content as well as soil enzyme activities at various depth intervals. Long‐term apple cultivation was effective to restore SOC stocks, although it took over a decade to rebuild a new increasing trend after farmland conversion.

Using Artificial Passageways to Facilitate the Movement of Wildlife on Namibian Farmland

Wildlife-proof fencing is increasing in extent as a result of the growing wildlife industry on private lands in southern Africa. In environments where such fences hinder the movements of free-ranging wildlife, the provision of artificial passageways can restore connectivity for some species. We tested the use of 49 discarded car tyres as wildlife passageways along the border of a Namibian wildlife farm. Tyres were installed into a wildlife-proof fence to reduce regular warthog (Phacochoerus africanus) damage to the fence and to provide connectivity and dispersal opportunities for selected indigenous wildlife species between adjacent farmland properties. The total cost for all 49 tyre installations was USD 252, which is significantly cheaper than daily fence patrols and maintenance. In addition, one tyre was monitored specifically for large carnivore activity with a motion-triggered camera trap (n = 96 trap days between August and December 2010). Eleven mammalian species used the tyre as a passageway and both cheetahs (Acinonyx jubatus) and leopards (Panthera pardus) made regular and repeated use of the tyre. Nine independent recordings of cheetahs, representing seven individuals, were made. One leopard was photographed four times. The suitability of discarded tyres as cost-effective artificial wildlife passageways for a range of mammalian species is stressed.

A comparison of streamflow, salt and water balances in adjacent farmland and forest catchments in south‐western Victoria, Australia

AbstractA study of the hydrologic effects of catchment change from pasture to plantation was carried out in Gatum, south‐western Victoria, Australia. This study describes the hydrologic characteristics of two adjacent catchments: one with 97% grassland and the other one with 62% Eucalyptus globulus plantations. Streamflow from both catchments was intermittent during the 20‐month study period. Monthly streamflow was always greater in the pasture‐dominated catchment compared with the plantation catchment because of lower evapotranspiration in the pasture‐based catchment. This difference in streamflow was also observed even during summer 2010/2011 when precipitation was 74% above average (1954–2012) summer rainfall. Streamflow peaks in the plantation‐based catchment were smaller than in the pasture‐dominated system. Flow duration curves show differences between the pasture and plantation‐dominated catchments and affect both high‐flow and low‐flow periods. Groundwater levels fell (up to 4.4 m) in the plantation catchment during the study period but rose (up to 3.2 m) in the pasture catchment. Higher evapotranspiration in the plantation catchment resulted in falling groundwater levels and greater disconnection of the groundwater system from the stream, resulting in lower baseflow contribution to streamflow. Salt export from each catchment increases with increasing flow and is higher at the pasture catchment, mainly because of the higher flow. Reduced salt loading to streams due to tree planting is generally considered environmentally beneficial in saline areas of south‐eastern Australia, but this benefit is offset by reduced total streamflow. Copyright © 2014 John Wiley & Sons, Ltd.

Small mammal community succession on the beach of Dongting Lake, China after the Three Gorges Project

Although the Three Gorges Project (TGP) may have affected the population structure and distribution of plant and animal communities, few studies have analyzed the effect of this project on small mammal communities. Therefore, the present paper compares the small mammal communities inhabiting the beaches of Dongting Lake using field investigations spanning a 20-year period, both before and after the TGP was implemented. Snap traps were used throughout the census. The results indicate that the TGP caused major changes to the structure of the small mammal community at a lake downstream of the dam. First, species abundance on the beaches increased after the project commenced. The striped field mouse (Apodemus agrarius) and the Norway rat (Rattus norvegicus), which rarely inhabited the beach before the TGP, became abundant (with marked population growth) once water was impounded by the Three Gorges Reservoir. Second, dominant species concentration indices exhibited a stepwise decline, indicating that the community structure changed from a single dominant species to a more diverse species mix after TGP implementation. Third, the regulation of water discharge release by the TGP might have caused an increase in the species diversity of the animal community on the beaches. A significant difference in diversity indices was obtained before and after the TGP operation. Similarity indices also indicate a gradual increase in species numbers. Hence, a long-term project should be established to monitor the population fluctuations of the Yangtze vole (Microtus fortis), the striped field mouse and the Norway rat to safeguard against population outbreaks (similar to the Yangtze vole outbreak in 2007), which could cause crop damage to adjacent farmland, in addition to documenting the succession process of the small mammal community inhabiting the beaches of Dongting Lake.

Effect of Land Use Patterns on Soil Aggregate Stability and Aggregate-associated Organic Carbon

To provide scientific evidence for coordinating regional land use and soil carbon pool management,it is essential to reveal the distribution of different sizes of soil aggregates and the aggregate-associated organic carbon after the Grain to Green Program.Eucalyptus grandis and Metasequoia glyptostroboides were the main afforestation species in the Grain to Green Program in Chengdu.Four typical land use patterns,namely,E.grandis,M.glyptostroboides plantations,the natural secondary forest of Pinus massoniana and the adjacent slope farmland,were selected as sampling plots to study the effects of land use change on aggregate stability and the aggregate-associated organic carbon in different soil layers(0-20 cm,20-40 cm and 4060 cm).The results showed that the macro-aggregates( 0.25 mm) dominated in the soil aggregate structure.The content of organic carbon in soil aggregates decreased with the increase of aggregate size.The proportion of the 0.25 mm fraction of soil aggregates,the mean weight diameter(MWD) of soil aggregates and the content of organic carbon in soil aggregate size increased after the Grain to Green Program.And the increase of content of organic carbon was largest in the 2 mm fraction of soil aggregates in the top 40-cm soil layer.Compared with those in the slope farmland,the proportion of organic carbon storage in the size of 2 mm soil aggregates increased by 5.96%-47.57% in other land use patterns,but decreased by 0.95%33.28% in the size of 0.053 mm soil aggregates.The natural secondary forest of P.massoniana had the highest total organic carbon storage of soil aggregates,while the farmland had the lowest total organic carbon storage among all land use patterns.The results indicated that E.grandis and M.glyptostroboides plantations have higher soil aggregate stability and organic carbon storage than the slope farmland,though still lower than the natural forest.

Soil organic matter dynamics after C3–C4 vegetation change of red soil in Southern, China: Evidence from natural 13C abundance

Soil samples from natural forests and adjacent farmland were analyzed to investigate the dynamics of soil organic matter of red soil in Southern, China. Based on the δ13C values and the content of soil organic matter, the data indicated that the turnover of soil organic matter under the virgin forest was slower than that under cultivation. Soil organic matter is fresh in coarse sand and oldest in fine silt and clay. Also, the soil light fraction contained the younger organic matter than soil heavy fraction and bulk soil. Deforestation has accelerated the decomposition rate of soil organic matter and reduced the proportion of active components in SOM and thus soil fertility.

Spatiotemporal variation in the microclimatic edge effect between wetland and farmland

The creation of wetland edges associated with anthropogenic fragmentation is common in wetland landscapes and brings about a unique microclimatic change that affects adjacent farmland. However, microclimatic edge effects within this kind of landscape are not well quantified. Thus, using a study site located in the northeastern Sanjiang National Nature Reserve, China, we investigated the spatiotemporal variations in the microclimatic variables of the surface layer across the wetland‐farmland edge. Air temperature and relative humidity data were collected continuously along a horizontal transect at four different heights over different periods, and the relative humidity was converted to specific humidity. Sigmoid models were used to fit the horizontal gradients of microclimatic edge effects. Then, based on the parameters in the fitted models, the characteristics of the edge effects were quantified with two indices, the magnitude of edge effect (MEE) and the spatial range of edge effect (REE). Under a light wind condition, the microclimatic features across the edge generally presented sigmoid ecological gradients in the horizontal direction, with unique spatial and temporal patterns: (1) In a normal year, wetland patches cooled and moistened the adjacent farmlands during the daytime and had a warming‐moistening effect during the nighttime. (2) Vertically, the absolute MEE value of the microclimatic variables decreased, but the REE increased with increasing height. (3) The MEE and REE for air temperature and specific humidity varied with the time of day, both shifting at dawn and dusk when the gradients were absent. (4) At the interannual scale, when compared to the farmland, the wetland was cooler at night in a dry year but warmer in a normal year. The detection of spatiotemporal microclimatic patterns in the wetland‐farmland edge zone may enable further understanding of how wetland degradation affects adjacent farmland ecology under human disturbance and promote better management and restoration of fragmented wetlands.

Effect Of Polluted Surface Water On Groundwater: A Case Study Of Budha Nullah

Groundwater is one of the most important natural resources. It is a major source of fresh drinking water in both the rural and urban regions. The groundwater quality, however in recent time has got deteriorated due to the percolation of polluted water in to the soils from the drains, polluted rivers and ponds. As a result its quality has not remained potable in many parts of the country. Contaminated groundwater of Mettupalayam Taluk in Tamil Nadu, Amravati River Basin of Karur District, Tamil Nadu, Eastern Uttar Pradesh are some of the example. Therefore, the evaluation of water quality of the rivers, groundwater and impact of polluted groundwater on environment and health has drawn attention of the researchers. The present thesis is also an attempt on such study. The pollution level of Budha Nullah water and its effect on groundwater and vicinity area have been studied in the present paper. Total eleven groundwater samples, seven Budha Nullah samples and five soil samples were collected from different locations within 6 km stretch of Budha Nullah and its adjoining areas. The samples of the different points were collected from handpumps and tubewells, the water from which is used for drinking and other purposes. All the quality parameters of these samples were analyzed using standard methods prescribed in Standard methods for examination of water and wastewater (18 TH edition). It was observed that pH of all the collected samples was within permissible limit of 6.5-8.5. The surface water analysis of Budha Nullah reveals high values of Total Dissolved solids up to 1642 mg/L, chlorides up to 400 mg/L, Chemical Oxygen Demand values up to 448mg/L, Biochemical Oxygen Demand varying between 52-195 mg/L, Most Potable Number varying from 240+ upto 2400+ per 100ml, heavy metal like Cr in the Budha Nullah has value 0.031 mg/L, Fe 0.913 mg/L, Mn 0.043 mg/L and Ni 0.222 mg/L. The quality of ground water at many places was found to be unfit for drinking mainly due to high amount of total dissolved solids and most potable number being much higher than the prescribed limit as per ISO 10500 standards. SAR of soil ranges from 3.78 to 6.98 mg/kg, which is optimum value for soil, as soils with SAR value less than 10 are considered good for leaching and water percolation. The reason behind the presence of other form of impurities and heavy metals in the ground water could be due to presence of heavy metals in surface water of Budha Nullah and its seepage in the adjacent groundwater aquifers. Objectives Of Study: The rapid industrialization in Ludhiana, though contributed to economic development, has resulted in heavy losses to economic welfare in terms of effects on agricultural activities, human health and ecosystem at large through air and water pollution. Solid and liquid wastes emanating from the industrial activities are the inevitable by-products of manufacturing process. These wastes contain toxic chemicals such as Chromium salts, sulfides and other substances including heavy toxic trace metals. These materials enter the surface water and subsurface aquifers resulting in water pollution. The town which earned the name of Manchester of Punjab landed into dubious distinction of being one of the most polluted human settlements in the country (G.S Gill et al.,1997). Similarly industries located in Mettupalayam taluk, Tamilnadu dispose their effluents on land, and the farmers of the adjacent farmlands have complained that their shallow open wells get polluted and also the salt content of soil has started building up slowly. Study found that continuous disposal of industrial effluents on land, which has limited capacity to assimilate the pollution load, has led to groundwater pollution (Mukherjee at el., 2006). In this dissertation an attempt has been made to study the water quality of the Budha Nullah and groundwater. Grab sampling was done from the different locations through the 12 km stretch of Budha Nullah in the Ludhiana city .

Accumulation of soil organic carbon in aggregates after afforestation on abandoned farmland

To understand how organic C (OC) accumulates in afforested soils and to quantify the contribution of aggregate-associated OC to OC accumulation, we investigated the changes in soil structure, total soil OC, and aggregate-associated OC from 0- to 10- and 10- to 20-cm depths in afforested forests and adjacent farmlands of northwestern China. We assessed the contribution of macroaggregate-associated OC increase to total soil OC accumulation. Afforestation increased macroaggregate amount, mean weight diameter, and mean geometric diameter but decreased the amount of microaggregate and silt + clay-sized fractions. The improvement of soil structure was greater in surface than subsurface soils and was greater in soils afforested with white birch than in soils afforested with other tree species. Fifty years after afforestation, total soil OC concentrations and stocks and aggregate-associated OC concentrations increased depending on soil depth and tree species. Afforestation increased macroaggregate-associated OC stocks but decreased microaggregate- and silt + clay-associated OC stocks. Soil OC stocks and changes in OC stocks after afforestation mainly depended on macroaggregate-associated OC stocks and their changes. The results from this study suggest that OC accumulation in afforested soils is due to the accumulation of OC in macroaggregates and the redistribution of OC from fine particles to coarser fractions.

Variation in Woody Species Abundance and Distribution in and around Kibale National Park, Uganda

Several protected areas in Uganda are increasingly facing encroachment making farmlands indispensable hubs for biodiversity conservation. A comparative study was conducted comprising a protected area in Kibale National Park and surrounding farmlands to establish how farmlands mimic the forest floristic structure. Study results show very low similarity between the forest and farmland ecosystems (CCj=0.11). A total of 50 and 29 species were identified in the forest and, farmland, respectively; 8 were shared. Importance value indices of woody species in the forest ranged from 0.3 to 29.9 with Celtis durandii being the most important while those in the farmland were 1.9–79.2, Eucalyptus grandis, having the highest index. Woody species diversity and evenness were higher in the forest ecosystem (H′=3.46, J′=0.85) compared to the farmland (H′=2.72, J′=0.79). The 10–<20 cm diameter class was the lowest in both ecosystems. Communities adjacent to the park should be educated about the value of the park and conservation in general. Since adjacent farmlands provide important ecotones to the park, on-farm indigenous tree retention and planting are required. Further research on threatened species is needed to enhance conservation in and around KNP.

Disturbance metrics predict a wetland Vegetation Index of Biotic Integrity

Indices of biological integrity of wetlands based on vascular plants (VIBIs) have been developed in many areas in the USA. Knowledge of the best predictors of VIBIs would enable management agencies to make better decisions regarding mitigation site selection and performance monitoring criteria. We use a novel statistical technique to develop predictive models for an established index of wetland vegetation integrity (Ohio VIBI), using as independent variables 20 indices and metrics of habitat quality, wetland disturbance, and buffer area land use from 149 wetlands in Ohio, USA. For emergent and forest wetlands, predictive models explained 61% and 54% of the variability, respectively, in Ohio VIBI scores. In both cases the most important predictor of Ohio VIBI score was a metric that assessed habitat alteration and development in the wetland. Of secondary importance as a predictor was a metric that assessed microtopography, interspersion, and quality of vegetation communities in the wetland. Metrics and indices assessing disturbance and land use of the buffer area were generally poor predictors of Ohio VIBI scores. Our results suggest that vegetation integrity of emergent and forest wetlands could be most directly enhanced by minimizing substrate and habitat disturbance within the wetland. Such efforts could include reducing or eliminating any practices that disturb the soil profile, such as nutrient enrichment from adjacent farm land, mowing, grazing, or cutting or removing woody plants.

Reforesting degraded agricultural landscapes with Eucalypts: Effects on carbon storage and soil fertility after 26 years

In the Western Australian wheatbelt, the restoration of native eucalypt forests for managing degraded agricultural landscapes is a critical part of managing dryland salinity and rebuilding biodiversity. Such reforestation will also sequester carbon. Whereas most investigative emphasis has been on carbon stored in biomass, the effects of reforestation on soil organic carbon (SOC) stores and fertility are not known. Two 26year old reforestation experiments with four Eucalyptus species (E. cladocalyx var nana, E. occidentalis, E. sargentii and E. wandoo) were compared with agricultural sites (Field). SOC stores (to 0.3m depth) ranged between 33 and 55Mgha−1, with no statistically significant differences between tree species and adjacent farmland. Farming comprised crop and pasture rotations. In contrast, the reforested plots contained additional carbon in the tree biomass (23–60Mgha−1) and litter (19–34Mgha−1), with the greatest litter accumulation associated with E. sargentii. Litter represented between 29 and 56% of the biomass carbon and the protection or utilization of this litter in fire-prone, semi-arid farmland will be an important component of carbon management. Exch-Na and Exch-Mg accumulated under E. sargentii and E. occidentalis at one site. The results raise questions about the conclusions of SOC sequestration studies following reforestation based on limited sampling and reiterate the importance of considering litter in reforestation carbon accounts.

Estimation of nitrogen flow within a village-farm model in Fakara region in Niger, Sahelian zone of West Africa

To determine the efficiency of utilization of organic matter in agricultural production, nitrogen flow was estimated within a village-farm model in the west of Niger, West Africa. Nitrogen was focused on in this study as it is known to be a major nutrient component of organic matter and one of the limiting nutrients in Sahelian soil. Local practices regarding the use of organic matter and pertinent information on traditional practices for soil fertility management were determined by interviews with local farmers. To estimate nitrogen flow in farmlands and consumption in the village through various activities, quantitative measurements of crop yield and organic amendment were carried out. Data on human and livestock excreta were taken from published reports. The size and classification of farmlands were as follows: 0.5 ha adjacent farmland, 1.6 ha threshing farmland, 6.0 ha transported-manure farmland, 5.5 ha corralling farmland, and 86.5 ha extensively managed farmland (EMF). Levels of nitrogen flow from these farmlands to the studied villages were 0.9, 2.9, 9.6, 15.2, and 94.2 Mg, while the flows to these farmlands were 14.6, 6.3, 13.7, 17.5, and 26.3 Mg, respectively. Upon calculation of nitrogen balance −8 kg ha−1 year−1 was estimated in EMF, but there was a positive balance in other types of farmland, which ranged from 4 to 262 kg ha−1 year−1, indicating inefficient use of nitrogen in the study area for crop production. The results indicated that nutrient flow in the study site was unequally distributed and nitrogen was not recycled. Therefore, efforts should be made to establish efficient utilization of available nutrients by reducing the loss from livestock feed and human consumption. At the same time, more research is needed to improve the management of EMF.