Introduction
Organic farming is lauded for its ability to sustain and enhance the health of the ecosystem and humans by producing high-quality and nutritious food (Murmu 2018; Meemken and Qaim 2018). It has garnered global attention and is viewed as a nature-based solution to mitigate climate change effects (Eco Voice 2021). With more studies emerging, it has become clear in recent years that organic practices can support agricultural production, confer resilience, reduce climate change impacts (Wani et al. 2013), and enhance nature and biodiversity (Tuck et al. 2013). In the Hindu Kush Himalaya (HKH), climate change can negatively impact crop production. The rising temperature is predicted to expand the geographic range of pests and diseases (Skendžić et al. 2021). The higher temperature is reported to cause a decline in soil moisture and affect soil fertility (Ostle et al. 2009).
Therefore, the changing climate can exacerbate the pest, disease, and soil fertility problems, which could hinder accomplishing the United Nation’s SDG 2 on achieving food security and promoting sustainable agriculture. However, organic farming is a climate-smart practice (Hamidov et al. 2018) and organic products command premium prices over conventional products and have good markets (Jeong and Jang 2019; Carlson and Jaenicke 2016). Hence, organic farming also plays a crucial role in reducing poverty (Anderberg 2020), prompting developing countries to emphasize organic practices in recent times. Nonetheless, compared to conventional farming, one of the main challenges of organic farming is limited options to manage pests and diseases (ElShafie 2019) and improve the nutrient status of infertile soils (Nandwani and Nwosisi 2016). Moreover, organic farming needs to balance a healthy ecosystem with affordable organic products (Meemken and Qaim 2018). Such a scenario demands a low-cost organic production system, possible only by using low-cost organic inputs. Jholmal, a homemade biofertilizer as well as pesticide, is a proven and successful technology in Nepal (Subedi et al. 2019). It is a low-cost and effective organic input that has helped smallholder farmers in Nepal maintain high agricultural productivity at low costs (Bhusal and Udas 2020). Jholmal is prepared by mixing in a defined ratio and fermenting farmyard manure (FYM), animal urine, water, and plants having insect repellent properties (Bhusal and Udas 2020; Subedi 2016). It is a good practice that could benefit countries like Bhutan considering its aggressive aspiration to pursue organic agriculture and become a fully organic country by 2035 (Kuensel 2020). Bhutan has a majority of its rural population engaged in cattle rearing (Wangchuk and Dorji 2008) and dung production for manuring is one of the objectives of cattle rearing in rural Bhutan. Although cattle dung is produced in huge quantities, Bhutanese farmers generally lack the knowledge of using it as a biofertilizer. The promotion of Jholmal in Bhutan is important because it could help diversify and optimize the use of cattle manure. Moreover, it supports the national objective to promote affordable technologies and bio inputs for organic agriculture in Bhutan (Department of Agriculture 2019). In this paper, we present the findings of field experiments in Bhutan where two different types of Jholmal biofertilizers were evaluated on chili (Capsicum annuum L.) crops. Chili was selected as an important ingredient in Bhutanese dishes and annually it is imported on a large scale to meet the domestic demand. Therefore, the objective of the study was to assess the effects of Jholmal biofertilizers on soil properties and chili yield.
Materials and methods
Study site Two field experiments were conducted at the College of Natural Resources in Punakha District, Bhutan, where the second experiment was conducted to validate the results of the first experiment. The experimental site was in west-central Bhutan (27°29'47.4"N 89°53'07.0"E), about
112 km (87 miles) east of the Paro international airport. The district has an elevation range from 1400 to 1800 meters above sea level and receives an annual rainfall of about 500 mm in winter and 1500 mm in summer with the annual temperature ranging from 5-30ᵒC (Punakha Dzongkhag Administration 2021). It lies in the subtropical region and experiences hot and dry summers with moderate winters. Paddy is the principal cereal crop in the area, followed by spring wheat. Chili production is also increasing in the district and is cultivated both in the dryland and wetland.
Experimental design and treatments Two separate experiments were conducted. The first experiment was carried out in 2020 from May to October
and the second experiment was in 2021 from March to August. Both experiments were carried out at the same site. The experiments were laid out inRandomized Complete Block Design (RCBD). There were three treatments and each treatment was replicated four times. Due to the lack of sufficient flat land on the sloping terrain, the individual plot size was maintained at 1 m × 3 m. Treatments were randomly allocated to the experimental plots. Three plots and four repetitions occupied a total area of 36 m2 . Seedbeds were raised to a height of 15 cm. A space of 35 cm was maintained between seedbeds as a buffer zone and also to allow for intercultural practices. The three treatments were Jholmal 1 (T1), Jholmal 2
(T2), and Control (T3). Jholmal 1 is used as a biofertilizer and Jholmal 2 is used as both biofertilizer and biopesticide. Control treatment did not receive fertilizer. Intercultural management was uniform for all plots. Chili (Capsicum annuum L.) variety Sha Ema was chosen as a test crop because it is popular among Bhutanese and forms the main ingredient of the national dish in Bhutan. Healthy chili seedlings at the two-three-leaf
stage were transplanted at a recommended planting distance of 40 cm × 40 cm row to row and plant to plant. Therefore, each plot (seedbed) had 14 plants and a total of 168 plants in 12 plots.
Jholmal ingredients, preparation method, and application Jholmal 1 and Jholmal 2 were liquid solutions, prepared following the procedures of Bhusal and Udas (2020) but with slight modifications in the quantities and ingredients used. Cattle dung was included in Jholmal 1 and not in Jholmal 2. Effective Microorganisms (EM) were included in both Jholmal treatments. EM is a mixed culture of beneficial naturally-occurring organisms that is applied as an inoculant. The ingredients and chemical properties of Jholmal 1 and Jholmal 2 are presented in Table 1 and Table 2.
All ingredients were mixed thoroughly. The mixture was left to ferment for two weeks at 15-30 °C in an air-tight container. During the fermentation period, the mixture was stirred once every day both clockwise and anticlockwise. After two weeks, the Jholmal biofertilizers were considered ready for use when the odor of urine disappeared and green color appeared at the top of the liquid.