Adoption of Good Agricultural Practice to Increase Yield and Profit of Ginger Farming in Nepal

Ginger is the most widely consumed spice in Asian countries. Besides spices, it has also been used as a traditional and herbal medicine in many parts of the world particularly for the treatment of nausea, vomiting, cough, arthritis, muscle pain, and asthma (Niebyl & Goodwin 2002; White 2007; Singletary 2010; Li et al. 2019). It is one of the major high-value cash crops and high-value exportable commodities grown in the mid-hills of Nepal. According to a recent report, Nepal produced 284,000 t of ginger from 23,000 ha of land in 2018 (FAOSTAT 2020). Nepal ranks as the fourth largest ginger-producing country in the world after India, China, and Nigeria. Ginger is one of the twelfth priority export commodities of Nepal (MOC 2016). However, the mean yield of ginger in Nepal is only 12.3 t·ha⁻¹ (MOALD 2018), which is almost 50% lower than the potential yield of 24.5 t·ha⁻¹ (Basnet & Gurung 2018).

Conventional farming in Nepal is mostly based on traditional knowledge and low farm inputs (Gairhe et al. 2018; Baral 2019; Subedi et al. 2020). Small-scale conventional farming, lack of improved cultivars, insufficient technical knowledge, limited extension services, and the incidence of rhizome rot and bacterial wilt are the key problems of ginger production in Nepal (USAID 2011; NARC 2014; Basnet & Gurung 2018). Rhizome rot and bacterial wilt are the common and devastating diseases of ginger that can cause more than 50% yield losses (Dohroo 2005; Stirling et al. 2009; NARC 2014). All these existing problems have constrained ginger yield below 15 t·ha⁻¹.

To meet the growing demand for food, there is a need to increase the yield and quality of food crops from a limited area (Tilman et al. 2011; FAO 2017; Calicioglu et al. 2019). The green revolution with the greater use of production inputs such as chemical pesticides and fertilizers, irrigation, new crop cultivars, genetically modified seeds, and improved technologies have significantly increased crop yield worldwide. However, the use of excessive amounts of synthetic pesticides and fertilizers in subsistence types of farming does not seem sustainable in the long term. Those chemical inputs can degrade soil, increase the concentration of toxins in ground and surface water, impose a risk to human health, damage the terrestrial and aquatic ecosystem, and increase production cost (Millennium Ecosystem Assessment 2005; Pimm et al. 2014; Jensen et al. 2020). Moreover, consumers are now more concerned about food safety and quality. Therefore, there is a need to find sustainable technologies that can help to increase yield and to protect our ecosystem and human health.

More importantly, the existing yield gap can be minimized by adopting best management practices (van Ittersum et al. 2013; van Wart et al. 2013; van Bussel et al. 2015). However, these practices should be economically viable and environmentally friendly. Organic farming is one of the sustainable production systems, but it could be expensive for small farmers of Nepal (Rana Bhat 2009; Banjara 2016). In this context, good agricultural practice (GAP) could be a better alternative to organic farming.

The GAP is a set of principles that apply to the farm production and post-production processes to produce safe and healthy food and non-food agriculture products, considering economic, social, and environmental sustainability (Hobbs 2003). A recent study conducted by Bairagi et al. (2019) found that the adoption of GAP could increase farm income by 6.2% and decrease the use of synthetic fertilizers by 31% for rice, lentil, tomato, and ginger in Nepal.

Many developed countries, such as Denmark, Australia, and the United States, have adopted the GAP package for integrated pest and nutrient management for decades (Waage 1998; Zalucki et al. 2009; Remáč 2018). In Turkey, GAP has been implemented as an alternative to organic farming (Akkaya et al. 2005). Also, in several Asian countries such as Nepal, India, Indonesia, Malaysia, Philippines, and Thailand, the GAP system has been implemented particularly in vegetable farming, focusing more on integrated pest and soil fertility management.

The Agriculture Development Strategy 2015–2035 of the Government of Nepal has given priority to GAP as a sustainable farming practice with the main focus on integrated plant nutrient and pest management (MOAD 2015). The Government of Nepal, Ministry of Agriculture, and Food and Agriculture Organization (FAO) have been promoting GAP through a participatory approach that is by organizing farmers’ field school (FFS) in some districts as a demonstration.

Many studies have found the positive impact of FFS on improving farmers’ knowledge and increasing the yield and income of small farmers (Godtland et al. 2004; Erbaugh et al. 2010; Davis et al. 2012). The participatory approach is considered an effective way to transfer knowledge-intensive technologies (Feder et al. 2003; Athipanyakul & Pak-Uthai 2012; Islam et al. 2012). In FFS, farmers gain practical experiences and improve their knowledge through a “learning-by-doing” approach where they work together in the field to reduce pesticide use, improve crop management, and secure better profit margins. It allows farmers to observe, measure, analyze, assess, and interpret key agro-ecosystem relationships as a basis for making informed management decisions (Braun et al. 2006).

However, due to limited government programs and the lack of GAP knowledge and awareness, the adoption of GAP is limited to very selected areas of Nepal. Moreover, to date, there is no scientific evidence found on the effect of GAP on ginger production.

Realizing the limitations of conventional farming and the importance of GAP, this study aimed to promote sustainable technology among ginger farmers of Nepal through a learning-by-doing approach. The main objective of this study was to compare the yield of ginger under different management practices and recommend the best practice in terms of yield, income, and environment.

The only significant differences at the 5% level were recorded for applied treatments (Table 4). No significant effects were obtained for the effects of location and the year of the experiment as well as for their interactions.

Figure 1 shows that T4 treatment resulted in a significantly higher rhizome yield (17.9 t·ha⁻¹) but did not differ statistically from T3 (17.5 t·ha⁻¹). The rhizome yield of GAP treatments was significantly different from traditionally produced rhizomes (T1 12.3 and T2 12.8 t·ha⁻¹). The study results showed a yield gap of 5.1 t·ha⁻¹ between the potential yield and the farmer’s actual yield. Likewise, the yields from treatments were about 2–4% higher if the mother rhizome was not harvested.

Fig. 1

The crop yield depends on many contributing factors such as weather, plant genotype, and management practice. In this experiment, we used high-yielding selected local cultivar, bio-pesticides, and chemical fertilizers and pesticides based on the actual need, dose, and soil fertility status. All other intercultural operations were followed as per the calendar of operations listed on GAP guidelines. The average growing season temperature and rainfall were found similar in each year of the experiment. Thus, we did not find a significant yield difference between three consecutive years of experiment. Similarly, the distance between the two locations was about 20 km where we found homogeneous soil types and weather patterns. Therefore, we also observed a similar yield in both locations.

But the yield and income varied greatly between traditional and GAP-adopted treatments and, to a lesser extent, between mother rhizome-harvested and not-harvested treatments. The higher yield obtained from the GAP in this study is consistent with the findings of Basnet & Gurung (2018) who reported a similar yield (17–22 t·ha⁻¹) of ginger in western Nepal under different management practices, including the use of improved ginger cultivar, mother rhizome harvest, and the use of Trichoderma and vermicompost.

Many studies have reported that vermicompost could be used as an alternative to synthetic fertilizers because it has a positive effect on improving soil fertility and yield of various crops (Alam et al. 2007; Manivannan et al. 2009; Isaac & Varghese 2016; Esmaielpour et al. 2020). Turmeric rhizome yields were found significantly highest (42.71 t·ha⁻¹) in the treatment applying vermicompost along with synthetic fertilizers in southern India (Isaac & Varghese 2016). Similarly, some studies found that various Trichoderma species are effective to manage rhizome rot disease in ginger and turmeric (Bharathi & Sudhakar 2011; Acharya et al. 2016; Thakur et al. 2017).

Application of Trichoderma solution can replace partly synthetic pesticides and insecticides (Tomer et al. 2018; Shashikumar et al. 2019; Maurya et al. 2020). The average yield of rice grown under GAP was increased by 1 t·ha⁻¹ in 2013 and 2.7 t·ha⁻¹ in 2014 comparing with the yield obtained from farmer’s own practices in Tanzania (Senthilkumar et al. 2018). Islam et al. (2012) found higher yield and income (1.7 times higher) from GAP-adopted tomato farming in Malaysia. Based on our results and previous study findings, we can confirm that good agricultural practices, such as integrated pest and soil nutrient management practices, improve ginger yield and net farm income.

Farmers remove mother rhizome during the rainy season (May–June) when the average temperature is usually 25 °C, relative humidity is above 70%, and soil moisture is high. This is a favorable condition to outbreak rhizome rot disease (Stirling et al. 2009; Le et al. 2014; Hossain et al. 2015). Moreover, the mother rhizome plays a vital role in the growth and development of plants because it reserves carbohydrates and protein (Gallagher et al. 1984; Steinmann & Brändle 1984; Le et al. 2014). The mother rhizome harvest in the main growth stage could cause mechanical injury, poor root growth, and decrease food reserve in the plant and ultimately leads to an increase in the chance of rhizome rot and other disease infection and yield reduction. Thus, the existing practice of mother rhizome harvest could be one of the reasons behind lower yield under T1 and T3 treatments.

Furthermore, the total production costs were almost similar in both traditional and under the GAP rules. But, the net farm income per hectare was found to be higher in the GAP treatments because the yield there was about 5 t·ha⁻¹ higher than that under the traditional practices. Comparably, the net farm income from mother rhizome-harvested treatments was much higher than that from the non-harvested treatments. The net farm income per hectare in GAP with mother rhizome harvest (T3) was more than twice as high ($2072.6) as in traditional practice (T1). It is because the ginger price is usually above $250·t⁻¹ higher during the time of mother rhizome harvesting and marketing than at the normal harvesting time (MOALD 2020). This is the main reason for harvesting mother rhizome in Nepal. Hence, the higher net income gained from the GAP with mother rhizome-harvested treatment in this study was due to increased yield and the higher market price at the mother rhizome marketing period. A similar net income was also reported by various studies conducted in different districts of Nepal (Timsina 2010; Poudel et al. 2016; Acharya et al. 2019). Based on the production cost and net farm income of each treatment, this study showed that the GAP-adopted production costs were not much different from the traditional ones, but the GAP treatments resulted in much higher income.

Table 6 shows that in Nepal the highest income per hectare could be achieved from large cardamom farming followed by ginger. It is true because the market price of large cardamom is much higher than that of other crops grown in this district, but this crop requires a specific production environment such as swampy land with high humidity, frequent irrigation, and shade (Shrestha et al. 2018). Those requirements are available in a limited area only. Thus, this study revealed that ginger production by adopting GAP rules has the comparative advantage in terms of net farm income over other alternative crops grown in Nepal. Therefore, with the government policy and interventions, this technology can be promoted wider. Further studies are needed to examine the potential effect of GAP with different doses of NPK or a combination of NPK with organic fertilizers and with different cultivars on ginger yield.

This study revealed that the ginger yield can be increased by 46% when grown under GAP rules without harvesting mother rhizomes. But, the highest net farm income (up to 60%) can be obtained from the GAP with mother rhizome harvest practice. Increased yield, higher BC ratio along with maximum net farm income, lower use of chemical inputs, high market price during mother rhizome harvesting time, and comparative benefit over other alternative crops found in the ginger farming adopting GAP with mother rhizome harvesting practice indicate that this practice could be the most profitable and sustainable farming practice for the ginger producers.