Hedgerow Intercropping Research Articles

Low-cost agroforestry technologies for climate change mitigation and adaptation in Sub-Saharan Africa: A review

Agroforestry encompasses a large set of techniques and practices that have the potential to improve farm productivity with minimum environmental impacts in the context of climate change mitigation and adaptation (CCMA). In this paper, we discuss the relevance of agroforestry technologies and practices for CCMA in Sub-Saharan Africa (SSA). We recorded 173 scholarly works and and reviewed 62. Our findings indicate that comprehensive and well-developed technologies are used in agroforestry systems in SSA. They can be classified into four main groups (intercropping, improved fallows, mulching and parkland) and seven sub-groups (relay cropping, hedgerow intercropping, rotational woodlots, coppicing fallows, farmer-managed regeneration, on-farm tree domestication through poly-propagation and mulching) based on factors including the origins and uses of the trees and the types of tree-crop association. Our review showed that the maximum positive effect of parkland agroforestry is obtained when tree density ranges from 20 to 40 tree/ha, indicating an increase in crop production of 915.9 kg/ha. Furthermore, overall, the returns to labour of techniques involving fertilizer trees outperform those for natural fallows by 17%. Agroforestry techniques contribute substantially to the REDD+ program, but the best techniques with the highest cost-benefit- ratio and a substantial CCMA effect appear to be the intercropping and improved fallow systems. However, we observed a lack of detailed context-specific economic, social and environmental costs for the different techniques. For effective and rational decision-making by farmers in their adoption of agroforestry, further research should focus on filling in the detailed economic, social and environmental costs of each technology in each specific context.

Adoption of Silvopastoral Agroforestry System for a Sustainable Cattle Production in Nigeria

Silvopastoral systems are agroforestry systems that involves a combination of tree growing with the production of livestock. This type of agroforestry system has the potential to improve hydric balance, enhances biodiversity conservation, increases organic livestock proximity index, allows cleaner cattle production, improves cattle production per hectare, improves carbon sequestration, reduce greenhouse gases and significantly reduce /eliminate herder -farmer conflicts in Nigeria . Hence, this paper reviews and introduces the adoption of silvopastoral agroforestry system for a sustainable cattle production in Nigeria using literatures. Types of silvopastoral systems includes Fodder bank systems, live fence or boundary systems, hedgerow intercropping systems and tree plantation with animal grazing systems. There is limited information on silvopastoral system in Nigeria, hence the need to carry out more research and studies on its acceptability and sustainability in the future.

Assessment of Existing Agroforestry Practices in East Hararghe Zone Oromia, Ethiopia

An agroforestry practice produces different benefits, which enhance household incomes and diversification of products. This study was aimed to identifying existing agroforestry practices and to identify perception behind of agroforestry practice and to identify the opportunities and major constraints related to agroforestry practices in Fedis, Kersa and Jarso Districts of the lowland, midland and highlands agro ecologies, of East Hararghe Zone, oromia, Ethiopia. The study was based on a household survey conducted on 154 farm household heads; focus group discussions, key informant interviews and direct field observations were applied. The data were analyzed using analytical (SPSS 20.0) software packages to calculate descriptive statistics. Chi-squared tests were used to compare the agroforestry practices and agro ecologies. The result indicates that six AFPs exist in the study area namely; scattered trees on croplands (58%), hedge row intercropping (33%), home garden (22%), multipurpose trees on farmland (19%), live fence /boundary planting (18%), and wind breaks (4%) were dominant. Significant respondent number (51.96%) of practices is involved in agri-silvicultural system, most of the farmer’s (45.12%) have positive attitude towards Agroforestry practices in the study area. Most of the respondents agreed on agro-forestry practices increased the construction input, soil fertility, food, and fodder. On the other hand, sacristy of land, moisture stress, diseases and pests, inadequate seedlings availability, and inadequate extension services are the major constraints . Results of the socio-economic characteristics respondents showed that gender, age, family size, and land holding positively and significantly influence the decision of the determined practice of household’s and were significantly affected the choice of agroforestry practice by the households. Based on the survey, it is concluded that scattered trees on farmland, hedge row intercropping, and home garden AFP dominant practices across agro ecologies and were the most appropriate agro-forestry practices. This agro-forestry practices increased the construction input, soil fertility, food, and fodder in the area of land sacristy, moisture stress, diseases and pests. Therefore, further the tree integration efforts of farmers should be guided by scientific principles, the interaction tree species with annual crops and economic analysis of the individual agroforestry practices, domestication of nitrogen fixing trees, fruit tree species, and promoting sustainable agroforestry should be carried out. Keywords: Agroforestry practices, indigenous knowledge, scattered trees on crop land, multipurpose tree, small holder farmers, and cash crops DOI: 10.7176/DCS/12-3-03 Publication date: March 31 st 2022

Assessment of Existing Agroforestry Practices in East Hararghe Zone Oromia, Ethiopia

An agroforestry practice produces different benefits, which enhance household incomes and diversification of products. This study was aimed to identifying existing agroforestry practices and to identify perception behind of agroforestry practice and to identify the opportunities and major constraints related to agroforestry practices in Fedis, Kersa and Jarso Districts of the lowland, midland and highlands agro ecologies, of East Hararghe Zone, oromia, Ethiopia. The study was based on a household survey conducted on 154 farm household heads; focus group discussions, key informant interviews and direct field observations were applied. The data were analyzed using analytical (SPSS 20.0) software packages to calculate descriptive statistics. Chi-squared tests were used to compare the agroforestry practices and agro ecologies. The result indicates that six AFPs exist in the study area namely; scattered trees on croplands (58%), hedge row intercropping (33%), home garden (22%), multipurpose trees on farmland (19%), live fence /boundary planting (18%), and wind breaks (4%) were dominant. Significant respondent number (51.96%) of practices is involved in agri-silvicultural system, most of the farmer’s (45.12%) have positive attitude towards Agroforestry practices in the study area. Most of the respondents agreed on agro-forestry practices increased the construction input, soil fertility, food, and fodder. On the other hand, sacristy of land, moisture stress, diseases and pests, inadequate seedlings availability, and inadequate extension services are the major constraints. Results of the socio-economic characteristics respondents showed that gender, age, family size, and land holding positively and significantly influence the decision of the determined practice of household’s and were significantly affected the choice of agroforestry practice by the households. Based on the survey, it is concluded that scattered trees on farmland, hedge row intercropping, and home garden AFP dominant practices across agro ecologies and were the most appropriate agro-forestry practices. This agro-forestry practices increased the construction input, soil fertility, food, and fodder in the area of land sacristy, moisture stress, diseases and pests. Therefore, further the tree integration efforts of farmers should be guided by scientific principles, the interaction tree species with annual crops and economic analysis of the individual agroforestry practices, domestication of nitrogen fixing trees, fruit tree species, and promoting sustainable agroforestry should be carried out.

Effects of Crop–Hedgerow Intercropping on the Soil Physicochemical Properties and Crop Yield on Sloping Cultivated Lands in a Purple Soil of Southwestern China

Crop–hedgerow intercropping systems are important agroforestry systems for preventing soil degradation and soil nutrient losses on sloping cultivated land in the Three Gorges Reservoir (TGR) area of China. However, the mechanism by which hedgerow spatial layouts and the planting patterns affect soil nutrients and crop yields is still uncertain. A two-year field experiment was performed on a 10° slope to investigate the effects of slope position and different crop–hedgerow intercropping systems on soil physicochemical properties and crop yields. The treatments were a two-belt mulberry contour hedgerow (TM), a two-belt compound mulberry–vetiver hedgerow (TCMV), a two-belt compound mulberry–alfalfa hedgerow (TCMA), a seven-year-old two-belt mulberry contour hedgerow (7YTM), a seven-year-old mulberry border hedgerow (7YBM), a seven-year-old pure mulberry (7YPM), and a control treatment (CT, no hedgerows). In all treatments, except 7YPM, there was a significant (p < 0.05) increase in crop yield, clay content, soil total nitrogen (STN), acid-hydrolyzable nitrogen (AHN), and soil organic carbon (SOC) with declining slope position, whereas soil bulk density (BD), sand content, and soil pH showed the opposite trend. In TM, TCMV, TCMA, and 7YTM, the mustard yields and soil properties were better than those in CT, and there was no significant (p > 0.05) difference in mustard yield or soil properties between the upper-middle and lower-middle slope positions. Compared with CT, TCMV, and TCMA increased mustard yields by 8.28% and 9.86%, respectively, while 7YTM, 7YBM, and 7YPM reduced mustard yields by 7.69%, 17.69%, and 29.73%, respectively. TCMV and TCMA were confirmed to be viable intercropping systems for significantly reducing nutrient losses, improving soil quality, and changing soil nutrient distributions to maintain optimum crop yields on sloping lands.

Evaluation and demonstration of leguminous shrubs hedgerows intercropping with maize crop

Smallholder farmers influenced from the challenges of production constraints to afford farm family with surplus food. To improve this problem the present study was designed to evaluate legume shrubs hedgerow intercropping with maize. In the present study, the growth performance of Sesbania sesban and Cajanus cajan was evaluated to determine their potential in hedgerow intercropping. The result revealed that Sesbania sesban performs better than Cajanus cajan in terms of biomass provision in the successive pruning, mean height, branching, diameter at breast height and root collar diameter. Biomass produced from Sesbania sesban was significantly higher than Cajanus cajan, this plays great role in soil nutrient improvement and maize yield also increased. There was an increasing trend in soil properties in terms of organic C, total N, in legume treatments especially in Sesbania sesban hedgerow to the initial and control soils. Maize grain yield higher under Sesbania sesban hedgerow plot than Cajanus cajan, maize with fertilizer and control. This should be intensively demonstrated to sustain the agricultural production as an organic farming through integration of easily adapting, less competing with the companion crop, deep rooted and fast growing legume tree/shrub species. Further research is important in areas of determining decomposing rate of different parts, pruned biomass and potential species should be identified.
 Int. J. Agril. Res. Innov. Tech. 11(1): 60-68, June 2021

Identifying optimal ridge practices under different rainfall types on runoff and soil loss from sloping farmland in a humid subtropical region of Southern China

The relationship between different rainfall types, different soil management practices, and soil erosion is not yet fully understood. In-situ observations of soil and water loss on sloping farmland in the red soil region of southern China with a subtropical monsoon environment were taken at 12 runoff plots with four treatments, i.e, downslope ridges, downslope ridges with hedgerow intercropping, contour ridges, and bare flat land as control, over a seven-year period from 2012 to 2018. During this time, 253 natural rainfall events were classified into three rainfall types by K-means clustering according to the rainfall depth, maximum-30 min rainfall intensity and rainfall duration, and surface runoff and soil erosion processes in relation to the rainfall types under different ridge practices were analyzed. The results show that water-induced soil erosion on the flat land control was significant, with average annual soil loss of 76.73 t·ha−1·yr−1, reaching the “intense erosion” classification, and ridge practices were confirmed to reduce annual runoff and soil loss in all rainfall events by 18.9–62.0% and 68.9–86.3%, respectively. On the whole, rainfall events can be divided into three types: intense, normal, and long-duration. Among them, intense and normal rainfall cause the majority of soil (88.5–93.7%) and water (75.0–83.8%) loss in this area, but the efficiencies in runoff and soil reduction during long-duration rainfall events were the lowest, or even negative on farmlands with only downslope ridges. 20% of the total rainfall events, in which 84.3–92.2% were intense and normal rainfall events, contributed to 29–33% of the total rainfall depth, 68–89% of the total runoff depth, and 94–98% of the total soil loss. Rainfall depth played a dominant role in generating runoff, while runoff accumulation was a main factor influencing on soil loss. Findings from our study indicate that by choosing a more appropriate ridge practice according to different rainfall types, there can be a positive effect on soil and water conservation.

Effect of alley plants species and plantain cultivars on yield of ita 331 upland rice in Umudike southern Nigeria

Alley cropping or hedgerow intercropping is one of the many sub-systems of agroforestry technology. A 5 x 3 factorial experiment in a Randomized Complete Block Design (RCBD) with three replications was used to determine the effect of four alley woody species and three plantain cultivars on the yield of ITA 331 upland rice grain in the 2017 and 2018 farming seasons. The Alley species, plantain cultivars and Alley species x plantain cultivars treatment interactions showed no significant effects (p>0.05) on ITA 331 upland rice grain yield. Student t-test on the two farming seasons showed significant increase in yield of ITA 331 upland rice grain in 2018 than in 2017. The non-significantly different rice grain yield in the alley species treatment plots could be due to the generally high nutrient release of the decomposed legume-based alley species. Agroforestry combination of alley plants species and plantain cultivars is suitable for ITA 331 upland rice production.
 Key words: alley cropping, yield, ITA 331 upland rice grain, alley woody species, plantain cultivars

Quantified Benefits of Cultivating Day-Lily (Hemerocallis citrina) Hedgerows over Multiple Years on Sloped Red-Soil Farmland, Southern China

Planting hedgerows is an effective measure for increasing soil and water conservation on sloped farmland, although the comprehensive and dynamic changes in benefits across the life span of the hedgerow are not fully understood. To expand our understanding in this area, day-lily (Hemerocallis citrina) was selected to research the effect of hedgerows built on sloped red-soil farmland in southern China. In situ observations of runoff and soil loss from 2012 to 2018 were recorded in triplicate for two treatments: (1) conventional downslope-ridge tillage (CT) and (2) hedgerow intercropping with downslope-ridge tillage (HT). Micro-topography, soil nutrient content, and crop yield changes in the study plots were recorded. Hedgerows began intercepting runoff and soil loss simultaneously from the second year after they were planted, reducing annual surface runoff (35–66%) and annual erosive sediment (32–87%). As hedgerows became established, they provided increasing positive effects on soil and water conservation. However, those beneficial effects were gradually obscured by changes in micro-topography. The presence of the hedgerow had no obvious influence on soil total nutrient contents under this experimental condition. On average, planting the hedgerow reduced peanut yield by 21% but reduced rapeseed yield only by 2%. Compared with CT treatment, the average economic output of HT treatment after reaching the hedge’s initial production was 1.52 times greater, showing a quadratic trend and reaching a maximum about 4 years after construction by regression. These findings indicate that hedgerow management could be optimized according to the desired beneficial soil and water conservation or crop yield characteristics in different developmental phases.

Effect of alley plants species and plantain cultivars on yield of 60-day cowpea grain in Umudike Southern Nigeria

Alley cropping or hedgerow intercropping is one of the many sub-systems of agroforestry technology. A 5 x 3 factorial experiment in a Randomized Complete Block Design (RCBD) with three replications was used to determine the effect of four alley woody species and three plantain cultivars on the yield of 60-day cowpea grain in the 2017 and 2018 farming seasons. The Alley species, plantain cultivars and Alley species x plantain cultivars treatment interactions showed no significant effects (p<0.05) on cowpea grain yield. Students t-test on the two farming seasons showed significant increase in yield of cowpea grain in 2018 than in 2017. Alley cropping technology could increase 60-day cowpea grain yield due to improved soil fertility in the system.
 Keywords: alley cropping, yield, 60-day cowpea, alley woody species, plantain cultivars

Agroforestry Practices and Carbon Sequestration Cost Estimates among Forest Land Dependent Households in Nigeria: A Choice Modelling Approach

Forest land use among farming households in Nigeria contributes adverse environment effect. The study assessed adoption and the cost implication of sustainable forest land use (agroforestry practices) among farming households in Nigeria forest reserves. A total of 300 farming households were randomly sampled using a multistage sampling technique. It was revealed that household size (p<0.01), non-farm income (p<0.01) and current farm debt (p<0.01) are main factors that exert influence on choice of agroforestry systems and consequently cost of carbon sequestration. The cost estimate of carbon sequestration among households revealed that the lowest cost of carbon sequestration was recorded from boundary planting system of agroforestry. If a total of 55 Mg C is sequestered per hectare per year, carbon would be sold as low as N1, 498.9 ≡$3.9. It was observed that planting trees haphazardly on farm plot will leave carbon sequestration cost at a range of $11.5 and $144. Likewise, hedgerow intercropping will yield a cost range of $63.5 and $38. The study therefore concludes that, boundary planting of trees around farm land provides a low cost of achieving carbon sequestration while addressing unhealthy forest land use among farming households in Nigeria.

Optimizing resource distribution and crop productivity in hedgerow intercropping by manipulating tree arrangement

The potential of tree arrangement in optimizing radiation and soil water distribution and crop yield of hedgerow intercropping systems was investigated using a Jatropha curcas–Pennisetum clandestinum (kikuyu) system (Ukulinga, South Africa). Treatments (1110 t ha−1) of Jatropha-only (JO), single-row Jatropha and kikuyu (SR), and double-row Jatropha and kikuyu (DR) were used. Treatments had asymmetrical radiation distribution across tree–crop (T–C) interfaces and different radiation interception by trees (JO: 27 %, SR: 11 %, DR: 8 %). Soil water varied among treatments and was asymmetrically distributed showing no consistent trend towards trees. Evapotranspiration was higher (p < 0.05) in SR than DR (13–65 %) and JO (16–37 %) for most part of the season. Estimated fine tree roots distribution was symmetrical in DR but not JO and SR. Total roots in SR were concentrated in the top 0.2 m (91 %) and beneath tree row (30 %), and varied inconsistently with distance from trees. Grass yields increased farther from tree rows and were higher in SR (8.7 t ha−1 in 2006–2007; 4.3 t ha−1 in 2007–2008) than DR (by <9 %). Radiation use efficiency of kikuyu (0.14–0.44 g MJ−1) also increased with distance from trees but irradiance correlated with grass yields poorly (R2 < 0.32) despite high rainfall and no nutrient limitation. Considering total productivity and evapotranspiration, DR was better tree arrangement than SR. Water availability dictated T–C interactions and intercrop yield more than radiation. It was possible to optimize radiation and water distribution and intercrop growth by manipulating tree arrangement without changing density.

An analysis of soil fractal dimension in a sloping hedgerow agroforestry system in the Three Gorges Reservoir Area, China

Hedgerow intercropping provides an efficient method of controlling soil erosion and improving soil fertility on sloping agricultural land. Topsoil (0–20 cm soil layer) of 32 plots established in the Three Gorges Reservoir Area of the Yangtze River was sampled from the steep land between hedgerows (P1) and within hedgerows uphill (P2), under (P3) and downhill (P4) from the hedgerow were analyzed and the soil volumetric fractal dimension (DV) was calculated and the relationships between DV and soil physicochemical properties were tested. Results show that hedgerows effectively intercept clay particles in soil; the soil clay concentration within hedgerows was significantly higher (P < 0.05) than that of the soil between hedgerows at P1, respectively. The soil DV varied significantly among different positions in hedgerow systems, the DV of soil within hedgerows at P2, P3 and P4 were significantly higher (P < 0.05) than that of the soil between hedgerows at P1. DV was correlated positively and very significantly (P < 0.01) with the soil clay concentration (R 2 = 0.93) and silt content (R 2 = 0.74), and the DV was significantly (P < 0.01) and negatively correlated with soil sand content (R 2 = 0.78). The DV was significantly correlated with various soil physical properties and concentrations of soil nutrients. Therefore, the DV can be considered as a potential and accurate evaluating indicator for soil quality and nutrient conservation as they relate to the hedgerow intercropping on steep land.

Combining δ13C measurements and ERT imaging: improving our understanding of competition at the crop-soil-hedge interface

Hedgerow cropping decreases erosion in hillside agriculture but also competes for water and nutrients with crops. This study combined two methods for an improved understanding of water and nutrient competition at the crop-soil-hedge interface. δ13C isotopic discrimination in plants and soil electrical resistivity tomography (ERT) imaging were used in a field trial with maize monocropping (MM) vs. leucaena hedgerow intercropping with and without fertilizer (MHF+ and MHF−) in Thailand. Hedges significantly reduced maize grain yield and aboveground biomass in rows close to hedgerows. ERT revealed water depletion was stronger in MM than in MHF+ and MHF- confirming time domain reflectometry and leaf area data. In MHF+, water depletion was higher in maize rows close to the hedge compared to rows distant to hedges and maize grain δ13C was significantly less negative in rows close to hedges (-10.33‰) compared to distant ones (-10.64‰). Lack of N increased grain δ13C in MHF- (-9.32‰, p ≤ 0.001). Both methods were correlated with each other (r = 0.66, p ≤ 0.001). Combining ERT with grain δ13C and %N allowed identifying that maize growth close to hedges was limited by N and not by water supply. Combining ERT imaging and 13C isotopic discrimination approaches improved the understanding of spatial-temporal patterns of competition at the hedge-soil-crop interface and allowed distinguishing between water and N competition in maize based hedgerow systems.

Can productivity and post-pruning growth of Jatropha curcas in silvopastoral systems be regulated by manipulating tree spacing/arrangement without changing tree density?

The potential of tree spacing/arrangement to alleviate effects of interspecific competition of hedgerow intercropping systems on productivity and response to pruning of Jatropha curcas (Jatropha) was investigated using a Jatropha – Pennisetum clandestinum (kikuyu) silvopastoral system at Ukulinga (KwaZulu Natal, South Africa). Treatments were differentiated by presence/absence of kikuyu and arrangement/spacing of Jatropha trees (one, two and three tree hedgerows on either side of the alley) and had the same tree density (1110 ha−1). When high water availability and kikuyu dormancy coincided, tree growth rates did not significantly differ across treatments. Trees of the treatment without interspecific competition (tree-only) were the tallest. Even when rainfall was high, post-pruning tree height growth rate was affected by belowground (BG) interspecific competition and tree spacing/arrangement. Treatment with a single tree hedgerow between alleys had the most frequent maximum stem growth rate and was the most efficient during limited water availability. Its trees showed slow initial response to pruning due to a high tree-grass interface, followed by compensatory growth when competition for water with grass was low. Generally, length of tree-grass interfaces affected yield inversely especially as trees matured toward their maximum-yield age (4–5 years). BG competition reduced tree yield more than tree biomass, while tree spacing/arrangement did not affect tree harvest index. Manipulation of tree arrangement/spacing without changing tree density had no consistent effects on tree productivity.

Mulching effects on water storage in soil and its depletion by alfalfa in the Loess Plateau of northwestern China

In the dryland region of the Loess Plateau of northern China, alfalfa (Medicago sativa L.) is widely grown for animal feed to develop livestock operations, while also reducing soil erosion and improving soil fertility/quality. A field experiment was carried out on a sandy loam soil from April 2007 to October 2012 to evaluate the processes of soil desiccation in the 500cm soil profiles, and the effects of mulch management on soil water content and temperature in the upper soil layer (5–15cm), water use efficiency (WUE) and forage dry matter yield (DMY) of alfalfa in rainfed pasture land. Three treatments were: no mulch control, gravel mulch and corn straw mulch. Corn straw and gravel were chosen, because these materials can be obtained easily in this region. Soil depth of water uptake by alfalfa moved down to deep soil quickly and seasonal rainfall became the main contributing factor after 5 years. The presence of straw on the soil surface reduced the maximum temperature, but it increased the minimum diurnal soil temperature. Straw mulch was more effective in regulating soil temperature than gravel in the pasture planting. Straw mulch and gravel mulch both enhanced soil water content at the 15cm depth. Straw mulch increased forage DMY of alfalfa by 420kgha−1 (by 6.7%) compared to no mulch control over the four growing seasons from 2009 to 2012, and gravel mulch reduced the forage DMY by 36kgha−1 (by 0.5%) during that period, but effects were not significant statistically. Straw mulch increased concentration of nitrate-N and available P in the upper soil layer significantly, and improved WUE. In conclusion, the findings suggest that alfalfa could extract water from progressively deeper soil layers and straw mulch was effective in minimizing fluctuations in soil temperature, and increasing water storage in surface shallow soil layers, forage yield and water use efficiency of alfalfa. Mulching grass hedges intercropping or contour hedgerow intercropping should be considered on sloping land.

Noninvasive Monitoring of Soil Water Dynamics in Mixed Cropping Systems: A Case Study in Ratchaburi Province, Thailand

Agriculture on shallow or steep soils in the humid tropics often leads to low resource use efficiency. Contour hedgerow intercropping systems have been proposed to reduce run‐off and control soil erosion. However, competition for water and nutrients between crops and associated hedgerows may reduce the overall performance of contour hedgerow systems. Electrical resistivity tomography (ERT) is a valuable technique used to assess the distribution and dynamics of soil moisture noninvasively. In this study, we demonstrated its potential to measure soil water depletion in the field in distinct cropping patterns in Ratchaburi province, Thailand. The measurements showed that the soils of our experimental plots were very heterogeneous both along the slope as with depth. This observation highlighted some constraints of the ERT method for soil moisture monitoring in the field, such as the difficulty of defining a relationship between electrical conductivity and soil moisture in very heterogeneous soils. Nevertheless, spatial analysis of the data revealed contrasting water depletion patterns under monocropping and intercropping systems. In this way, ERT provides access to information about the vadose zone moisture dynamics that would be unavailable with classical soil moisture measurements.

Can We Use Electrical Resistivity Tomography to Measure Root Zone Dynamics in Fields with Multiple Crops?

Contour hedgerow intercropping systems have been proposed to reduce run-off and control soil erosion on steep agricultural land. However, competition for water and nutrients between crops and associated hedgerows may reduce the overall performance of these systems. ERT measurements conducted in Thailand showed that the soils of our experimental plots were very heterogeneous both along the slope as with depth. This observation highlighted some constraints of the ERT method for soil moisture monitoring in the field. Nevertheless, the data indeed revealed contrasting water depletion patterns under monocropping and intercropping systems, which could also be related to plant parameters.

Evaluating Experimental Design of ERT for Soil Moisture Monitoring in Contour Hedgerow Intercropping Systems

Contour hedgerow intercropping systems have been proposed as an alternative to traditional agricultural practice with a single crop, as they are effective in reducing run‐off and soil erosion. However, competition for water and nutrients between crops and associated hedgerows may reduce the overall performance of these systems. To get a more detailed understanding of the competition for water, spatially resolved monitoring of soil water contents in the soil‐plant‐atmosphere system is necessary. Electrical resistivity tomography (ERT) is potentially a valuable technique to monitor changes in soil moisture in space and time. In this study, the performance of different ERT electrode arrays to detect the soil moisture dynamics in a mono‐ and an intercropping system was tested. Their performance was analyzed based on a synthetic study using geophysical measures, such as data recovery and resolution, and using spatial statistics of retrieved water content, such as an adjusted coefficient of variation and semivariances. The synthetic ERT measurements detected differences between the cropping systems and retrieved spatial structure of the soil moisture distribution, but the variance and semivariance were underestimated. Sharp water content contrasts between horizons or in the neighborhood of a root water uptake bulb were smoothened. The addition of electrodes deeper in the soil improved the performance, but sometimes only marginally. ERT is therefore a valuable tool for soil moisture monitoring in the field under different cropping systems if an electrode array is used which can resolve the patterns expected to be present in the medium. The use of spatial statistics allowed to not only identify the overall model recovery, but also to quantify the recovery of spatial structures.

Bio-economic analysis of soil conservation technologies in the mid-hill region of Nepal

Soil degradation is a major threat to agricultural sustainability in Nepal. Increased anthropogenic activities in the inherently fragile ecosystem of unstable geology, steep slopes and intense monsoon rains have accelerated the loss of soil and its fertility in the Nepalese hills. This paper assesses soil conservation technologies from biophysical and economic perspectives using the integrated bio-economic analysis. The study applied a biophysical model, Soil Change Under Agroforestry (SCUAF), to project effects of the conservation technologies on soil erosion control as well as on crop yields over a thirty-year period. The technologies considered are hedgerow intercropping and minimum tillage. The outcome of the biophysical model was integrated into a cost-benefit analysis to examine the economic viability of the technologies. The results showed that these technologies are effective in reducing a substantial rate of soil erosion prevailing in the conventional system of maize cultivation. They have a variable impact on yield maintenance and the farmers’ economic return over time. The hedgerow intercropping sustained crop yields in the long-term although yield was reduced in the short-term. Likewise, high costs for establishing and maintaining the hedgerow intercropping significantly reduced farmers’ economic returns in the short-term. Minimum tillage technology, while better than the conventional farming system, was not able to sustain crop yield in the long-term. Yet, it provided positive returns for a longer period than the conventional system. The study concludes that though the evaluated technological options are effective in reducing the high rate of erosion resulting from the conventional maize cropping system, economically they are not viable for farmers in the short-term. Therefore, to expedite the wider adoption of these technologies and to halt and reverse soil degradation, it is suggested that farmers initially be supported with economic incentives to compensate their short-term economic loss.