Spatial variability of soil properties under different land use in the Dang district of Nepal

Increased nutrient mining, soil erosion, and limited nutrient management has led to declines in soil quality and reduced productivity in many parts of Nepal. A study was conducted in the eastern part of the Dang district of Nepal in 2015 to assess the variability of selected soil properties of three different land use types (agricultural, agroforestry, and grassland) and to map their spatial distribution. A total of 120 soil samples were collected from 0–15 cm depth and analyzed for soil fertility parameters: pH, organic matter (OM), nitrogen (N), phosphorus (P), potassium (K), boron (B), and zinc (Zn). Results revealed that the average value of the soil pH significantly (P \u3c 0.05) varied from agroforestry to agricultural land use. Soil OM and N contents were in the medium range in all land use with minor variation, with the highest average OM and N found in grassland (2.87% and 0.14%), followed by agricultural land (2.64% and 0.13%), and agroforestry (2.45% and 0.12%). Soil P showed a significant variation between agroforest (18.99 kg ha−1) and grassland (8.49 kg ha−1). Soil K content was high in grassland (144.44 mg kg−1) and low in agricultural land (120.95 mg kg−1) but was not statistically significant. Micronutrient B was low (0.28–0.35 mg kg−1) and Zn was very low (0.14 mg kg−1). The interpolated soil maps thus generated may assist farmers in identifying the expected nutrient levels for their localities and encourage them to modify their management practices to improve productivity and lift income

Spatial variability of soil properties under different land use in the Dang district of Nepal

Increased nutrient mining, soil erosion, and limited nutrient management has led to declines in soil quality and reduced productivity in many parts of Nepal. A study was conducted in the eastern part of the Dang district of Nepal in 2015 to assess the variability of selected soil properties of three different land use types (agricultural, agroforestry, and grassland) and to map their spatial distribution. A total of 120 soil samples were collected from 0–15 cm depth and analyzed for soil fertility parameters: pH, organic matter (OM), nitrogen (N), phosphorus (P), potassium (K), boron (B), and zinc (Zn). Results revealed that the average value of the soil pH significantly (P \u3c 0.05) varied from agroforestry to agricultural land use. Soil OM and N contents were in the medium range in all land use with minor variation, with the highest average OM and N found in grassland (2.87% and 0.14%), followed by agricultural land (2.64% and 0.13%), and agroforestry (2.45% and 0.12%). Soil P showed a significant variation between agroforest (18.99 kg ha−1) and grassland (8.49 kg ha−1). Soil K content was high in grassland (144.44 mg kg−1) and low in agricultural land (120.95 mg kg−1) but was not statistically significant. Micronutrient B was low (0.28–0.35 mg kg−1) and Zn was very low (0.14 mg kg−1). The interpolated soil maps thus generated may assist farmers in identifying the expected nutrient levels for their localities and encourage them to modify their management practices to improve productivity and lift income

Spatial variability of soil properties under different land use in the Dang district of Nepal

Increased nutrient mining, soil erosion, and limited nutrient management has led to declines in soil quality and reduced productivity in many parts of Nepal. A study was conducted in the eastern part of the Dang district of Nepal in 2015 to assess the variability of selected soil properties of three different land use types (agricultural, agroforestry, and grassland) and to map their spatial distribution. A total of 120 soil samples were collected from 0–15 cm depth and analyzed for soil fertility parameters: pH, organic matter (OM), nitrogen (N), phosphorus (P), potassium (K), boron (B), and zinc (Zn). Results revealed that the average value of the soil pH significantly (P \u3c 0.05) varied from agroforestry to agricultural land use. Soil OM and N contents were in the medium range in all land use with minor variation, with the highest average OM and N found in grassland (2.87% and 0.14%), followed by agricultural land (2.64% and 0.13%), and agroforestry (2.45% and 0.12%). Soil P showed a significant variation between agroforest (18.99 kg ha−1) and grassland (8.49 kg ha−1). Soil K content was high in grassland (144.44 mg kg−1) and low in agricultural land (120.95 mg kg−1) but was not statistically significant. Micronutrient B was low (0.28–0.35 mg kg−1) and Zn was very low (0.14 mg kg−1). The interpolated soil maps thus generated may assist farmers in identifying the expected nutrient levels for their localities and encourage them to modify their management practices to improve productivity and lift income

Changes in soil organic carbon fractions in abandoned croplands of Nepal

Cropland abandonment in Nepal is an emerging land use change that has significant impacts on ecosystem functions, particularly soil organic carbon (SOC) pools and stocks. Information relating to SOC is limited for the mountainous terrain of Nepal that is subject to either SOC loss from erosion or SOC accumulation from secondary succession after cropland is abandoned. The rate of cropland abandonment is accelerating in Nepal but the impact of the abandoned duration on SOC, fractions, and SOC stock has not yet been investigated. We used a space-for-time substitution approach to assess the impacts of abandonment on SOC concentrations, stocks and associated pools of carbon across abandoned cropland ( 10 years) compared with forest, pasture, and currently cropped land. Soil samples were collected at four depth increments (0–10, 10–20, 20–40, 40–60 cm). The change in SOC and stock was found to be significantly higher in the surface (0–20 cm) compared with sub-surface soil (20–60 cm) and consistently decreased with increasing soil depth under all land uses. Change in soil nitrogen concentration followed a similar pattern to that of SOC at all land uses and depths. Among the SOC fractions, particulate organic carbon increased significantly by a greater proportion compared to mineral-associated organic carbon and dissolved organic carbon after 10 years of cropland abandonment. Abandoned cropland >10 years had a higher SOC stock (64.19 Mg ha10 years had a higher SOC stock (64.19 Mg ha−1) in the soil profile (0–60 cm) compared with cropped land (58.76 Mg ha−1) although it remained lower than forest (66.56 Mg ha−1) and pasture (66.60 Mg ha−1) soils. Although there was a decrease in the first five years, there was a significant accumulation of SOC, associated fractions, and SOC stock after ten years of abandonment and colonisation by vegetation indicating the inception of ecosystem regeneration in abandoned croplands in the mountainous region of Nepal

Pasture Species as an Option for Soil Organic Carbon Sequestration to Restore Abandoned Croplands in Nepal

Cropland abandonment is a human-induced land use change that is emerging globally in the last century. The rate of cropland abandonment is increasing in Nepal in the last decade, impacting soil functions and productivity. Restoration options have been actively sought by land managers and policymakers, and the potential of pasture establishment has been seen as a potential option to maintain soil quality while also providing a productive base for landholders. Following abandonment, changes in geomorphology and secondary vegetation succession can have a significant impact on soil organic carbon (SOC). Few studies have been conducted in Nepal to understand the impact and restoration of post-abandonment land. In this work, abandoned croplands, forest, pasture, and existing cropped land were examined in Gorkha and Kavre districts of Nepal with the aim of understanding the impacts of cropland abandonment by measuring the change in SOC across soil depths. A field experiment was undertaken in Gorkha district of Nepal where four pasture species were grown in a prior cropland abandoned for 2 years, in order to understand the potential of pasture species for carbon (C) sequestration. To explore the mechanism of SOC formation by pasture roots, a greenhouse experiment at University of New England, Australia was also conducted in which four pasture species were grown in two contrasting soil types (Ferrosol and Chromosol). Abandoned cropland in Nepal subject to secondary vegetation succession had accumulated significant amounts of SOC, particularly the labile fraction (particulate organic carbon), compared with existing cropland, especially after 10 years of abandonment and that SOC values were on the trajectory towards those of forest and pasture. Around 23% of SOC has been recovered with secondary succession in more than 10 years abandoned cropland compared to the currently cropped land. Pasture establishment on abandoned cropland increased the SOC in which the labile carbon increased in the top-soil (0-20 cm) and stable carbon in sub-soil (20-40 cm). Pasture roots contribute to form new carbon through dissolved organic carbon formation and root exudation that is mostly fixed on the stable SOC fractions (mineral-associated organic carbon) in both Chromosol and Ferrosol. It is concluded that vegetation cover in abandoned cropland increased labile carbon in the surface soil which had been preferentially lost in the early years of abandonment. With the pasture establishment on abandoned cropland, SOC can be stabilised in sub-soil with the higher fixation of new carbon in the mineral soil matrix. So, we recommend that land managers and policymakers integrate a pasture component in abandoned cropland restoration program that has ability to restore abandoned cropland through increased SOC

Potassium nutrient response in the rice-wheat cropping system in different agro-ecozones of Nepal.

Most of the soils of Nepal had a higher potassium (K, expressed as K2O) level inherently. Later in 1976, the Government of Nepal has recommended K fertilizer rate at 30 kg K2O ha-1 in rice-wheat cropping systems. However, those crops began showing K deficiency symptoms in recent decades, which could be due to a large portion of soils with depleted K level or the insufficient input of K fertilizer for crop production. This study explored a limitation of K nutrient in the crops by establishing field trials from 2009-2014 at three agro-ecozones i.e., inner-Terai (2009-2010), high-Hills (2011-2012), and Terai (2012-2014) in Nepal. Seven rates of K fertilizer at 0, 15, 30, 45, 60, 75, and 90 kg K2O ha-1 were replicated four times in a randomized complete block design, where crop yields and yield-attributing parameters of rice-wheat cropping system were recorded. Results revealed that an increase in K rates from 45 to 75 kg K2O ha-1 under inner-Terai and Terai conditions and 45 to 60 kg ha-1 under high-Hills conditions produced significantly higher grain yields compared to the recommended K dose. Economically, the optimum rate of K fertilizer should not exceed 68 kg K2O ha-1 for rice in all agro-ecozones, or 73 kg K2O ha-1 for wheat in inner-Terai and 60 kg K2O ha-1 for wheat in high-Hills and Terai. Our findings suggest to increase potassium application in between 1.5 to 2.5 times of the current K fertilizer rate in rice-wheat cropping system of Nepal that need to be tested further in different locations and crop varieties

Agricultural Land Abandonment in the Hill Agro-ecological Region of Nepal: Analysis of Extent, Drivers and Impact of Change

Despite widely reported trends of agricultural land abandonment across many parts of the globe, this land use change phenomenon is relatively new in the context of Nepal. In recent years, rural farming communities in the hill region are gradually reducing the intensity of farming, leading to underutilisation and abandonment of agricultural lands. Adopting a mixed methods research approach, this study investigated the extent of agricultural land abandonment, its underlying causal drivers and perceived impacts in the hill agro-ecological region of Nepal. A structured survey of 374 households and six focus group discussions were carried out in three districts. The study revealed that around 40% of agricultural lands in the hill agro-ecological region have been abandoned and 60% of farmers have left at least one parcel of agricultural land abandoned. It was found that biophysical drivers (distance from homestead to parcel, slope of the parcel, land fragmentation, land quality and irrigation availability) and socio-demographic drivers (family size, higher education of the household members, domestic migration and out-migration) were responsible for agricultural land abandonment. Negative impacts of land abandonment were observed on the rural landscape, human-made farm structures, socio-economic systems, local food production and food security. In line with global studies, this research suggest that marginal land quality, demographic changes and rising alternative economic opportunities elsewhere contribute to farmland abandonment. This study also discusses land management approaches and policy implications to address the issue of agricultural land abandonment

Performance of Tomato with Organic Manures in Plastic Tunnel

Tomato is one of the most demanded vegetable with increasing trend of commercial cultivation in Nepal. As it is the heavy feeder crop thus soil nutrient management has been always challenging. Since, in modern world organic production has been favored by consumers for many reasons thus we aimed to compare the efficacy of various compost, mineral fertilizers and their combinations in tomato production and soil productivity. For the purpose a field experiment in plastic tunnel was carried out in Horticulture Research Division, Khumaltar in two consecutive years (2014 and 2015). Srijana, a popular tomato hybrid among commercial producers, was purposively selected. Eight treatments (control, recommended doses of chemical fertilizers, compost 15 t ha-1 + cattle urine, compost 10 t ha-1 + cattle urine, compost 12.5 t ha-1 + cattle urine, compost 15 t ha-1 + 1/4 recommended dose of chemical fertilizers, compost 10 t ha-1 + ¾ recommended dose of chemical fertilizer and compost 12.5 t ha-1 + 1/2 recommended dose of chemical fertilizer) were laid out in randomized complete block design and replicated thrice. The result showed significant (p < 0.05) positive correlation between the plant height and yield of tomato. The treatment with compost dose of 12.5 t ha-1 with half dose of recommended dose of chemical fertilizers produced the highest incremental yield (85% increment) over other treatments followed by compost 15 t ha-1 with cattle urine. Addition of soil organic carbon, soil nitrogen, soil potassium by the increasing level of compost though not significant, but increment in carbon content, nitrogen content and potassium content of soil observed in successive years. For commercial producer at plastic tunnel, compost at the rate 12.5 t ha-1 with half dose of recommended level of chemical fertilizer (100:90:40 kg N:P:K ha-1) is recommended to apply in field, while for organic producer, application of 15 tha-1 compost with fermented cattle urine is recommended

A systematic review and gap analysis of drivers, impacts, and restoration options for abandoned croplands in Nepal

Cropland abandonment is an emerging human-induced land use and is a growing national problem in Nepal. It is a key, current concern for local governance bodies and restoration options for this land are being actively sought. We initiated a systematic review of existing studies to identify the key causes and impacts of cropland abandonment and consider a range of restoration options. Data on the drivers, impacts, and restoration options for abandoned cropland were extracted from current relevant literature retrieved through four databases (Web of Science, Google Scholar, Scopus, and NepJol). Most studies focused on the drivers of cropland abandonment with less focus on the impacts and restoration options. Socio-economic drivers included outmigration, limited availability of labour or high labour cost, easy access to daily supply needs and high education level of the farming family members. Bio-physical factors were also reported as key drivers of cropland abandonment including unsuitable slope and rugged land topography, low soil fertility and low crop productivity. Both positive and negative impacts of cropland abandonment were also reported, principally bio-physical such as secondary vegetation succession as a positive impact and geomorphic damage and low crop production as negative impacts with a consequent decrease in food security. Most current studies focused principally on specific sites and typically lacked restoration options coordinated at a national level. Those studies that did identify restoration options for abandoned land suggested the adoption of short crop cycle, less labour-intensive crops, agro-forestry and conversion to pasture as key options. Most, however, failed to establish linkages between food insecurity, rural livelihoods, and ecosystem services after cropland is abandoned. As prior studies on abandoned land lack a defined study framework, we recommend an integrated research approach for Nepal. The approach suggests the need to adopt an integrated way for studying abandoned cropland restoration through the empirical analysis of local and national land abandonment issues. The proposed approach could also be applied in other areas where cropland abandonment is an issue

Effects of different fertilizer sources on growth and yield of broccoli in Chitwan, Nepal

To study the effect of different fertilizer sources on yield, growth and soil organic matter in broccoli, a research was conducted at Agriculture and Forestry University, Chitwan, Nepal from Sep, 2015 to Feb, 2016. The research consisted of ten treatments viz; recommended chemical fertilizer, Farm Yard Manure (FYM), Vermi-compost (VC), Cow urine (CU), Bio organic fertilizer (BOF), (NPK 50%+FYM 50%), (FYM 50% + CU 50%), (FYM 50 % + VC 50%),(FYM 50% + BOF 50%) and {25% (FYM+VC+CU+BOF)} in randomized complete block design replicated three times. The study revealed that the curd yield (10.63 t ha-1), dry matter production (6.34 t ha-1) and leaf area index (5.12) were observed highest at recommended NPK treatment. Among the organic treatments, (FYM 50%+cow urine 50%) combination showed the highest curd yield (7.79 t ha-1), dry matter production (5.49 t ha-1) and leaf area index (4.95). The highest soil organic matter content (2.85 %) was found at (FYM 50%+ VC 50%) treatment and lower (2.06%) was recorded in NPK applied treatment. Thus, the result showed that chemical fertilizer produced the higher yield in first season but the ecological benefits of these fertilizers are relatively less than other organic fertilizers