Faculty Publications
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Item Evolution of Fertiliser Use and its Impact on Maize Productivity in Kenya: Evidence from Multiple Surveys(Springer Science and Business Media B.V., 2021) Jena, P.R.; De Groote, H.; Nayak, B.P.; Hittmeyer, A.During the 1990s, the Kenyan agricultural sector became increasingly liberalised. For many years, both government- and non-government organisations have advised farmers on fertiliser doses, and therefore, an increase in fertiliser adoption resulting in higher yields has been expected. We analyse the evolution of fertiliser use and its impact on maize productivity and household incomes in Kenya, using four household surveys conducted between 1992 and 2013. Each survey represented all six maize-producing zones of Kenya. The results show that the percentage of fertiliser users among maize farmers has increased slightly over the years (from 62% in 1992 to 65% in 2013), and the quantity of fertiliser applied per ha has increased (from 82 kg/ha in 1992 to 100 kg/ha in 2013) but remains far below recommended levels. Therefore, maize yields have remained stagnant, or even decreased slightly (from 1360 kg/ha in 1992 to 1116 kg/ha in 2013). We also observe that the following factors affect fertiliser use and maize yields: education of the household head; area under maize cultivation; agroecological zone; uneven access to extension services; and food insecurity. We also find that fertiliser use has a positive impact on both maize yields and household income. We conclude that the liberalisation of fertiliser markets in Kenya did not have the desired effect of increasing fertiliser use and consequently maize yields, except in the high potential maize-growing areas. Possible explanations include both market factors, e.g. high prices, and non-market factors, e.g. access to information. We make two policy recommendations based on these findings – firstly, the targeted outreach of extension services should be considered, to increase fertiliser use and yields in less-productive regions, and secondly, policies should be considered that incorporate provisions for weather shocks. © 2020, International Society for Plant Pathology and Springer Nature B.V.Item Bivariate Drought Characterization of Two Contrasting Climatic Regions in India Using Copula(American Society of Civil Engineers (ASCE), 2021) Sajeev, A.; Deb Barma, S.; Mahesha, A.; Shiau, J.-T.This study aims to construct the multiple time-scale joint distributions of drought duration and severity using two-dimensional copulas and compare the drought characteristics in India's two contrasting climate regions: the arid Rajasthan and humid, tropical Kerala. The drought occurrences were defined by the standardized precipitation index (SPI) with a threshold below -0.8 at time scales of 3, 6, 12, and 24 months for 1900-2016. Significant correlations were noted between the drought severity and drought duration in both regions. The Clayton copula gave a better fit than other copulas for modeling the dependence among the observed drought duration and severity. The results indicate that the probability of short-term droughts (SPI-3 and SPI-6) is more significant than those of long-term droughts (SPI-12 and SPI-24) for an identical drought event in both regions. Also, the probability of severe drought events with greater duration and severity for long-term droughts (SPI-12 and SPI-24) is higher in Kerala than that in western Rajasthan. For all the time-scale SPIs, the conditional probability of drought severity for a given duration exceeding a threshold showed an increasing trend in both regions. Furthermore, the conditional probability of the drought duration given the severity for short-term droughts is greater than that of the long-term droughts for the same drought event. For short-term droughts, the conditional return period of an identical drought event is lower in Kerala than in western Rajasthan. In contrast, the conditional return period of long-term droughts is lower in western Rajasthan. Additionally, copula-based nonexceedance conditional distributions for the major crops were established based on rainfall. © 2020 American Society of Civil Engineers.Item Community input to quantification of lake restoration benefits: a pilot study of coastal Karnataka Lake, India(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, S.T.; Shetty, A.; Varadaraj, K.S.Lake restoration is one of the regional initiatives aimed at increasing natural resource-based livelihoods. Typically, data on lake inflows/outflows or benefits are not available. Under the circumstances, the best way to collect data is through a questionnaire survey and interviews with residents of the area. The study aims to determine the present condition of the lake and quantify the advantages of the lake on crop productivity after and before the construction of the bund. A reconnaissance investigation of the area found that the lake might have an impact within a 5 km radius. As a result, a survey was carried out within a 5 km radius. The total amount of lake water used for agriculture is 33264 mm3. The incorrect management of the lake's water has resulted in a water deficit in the study region. Consequently, residents who benefit from the lake are increasingly dependent on alternative water sources, such as wells and small ponds. As a result, the yield decreased by 20.45%. After the bund construction was built across the outflow of lake water, the profit increased by 37.88%, making more water available throughout the year. According to the study, appropriate conservation efforts require community input. Instead of focusing on high-cost technology in coastal Karnataka, this study suggests that water resource managers should restore surface water bodies, providing more water benefits for the public. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.