Effects of weather extremes on crop yields in Nigeria

Abstract

This study seeks to analyze how extreme weather conditions affect crop yield and risk in Nigeria and to assess the potential implications of weather extremes on the nation's crop insurance portfolio. A panel of Nigerian state-level crop yields was paired with a finescale weather data set that included distribution of temperature and precipitation between the minimum and maximum across all days of the growing season for selected crops. Weather data were examined from January 1, 1991 to December 31, 2012. The analysis was started with the traditional approach of estimating climate change impact by a quadratic regression model of weather and Growing Degree Days (GDD) on crop yields using panel data estimation. Later, Harmful Degree Days (HDD) and Vapour Pressure Deficit (VPD) were stepwisely included. Interactions of rainfall, GDD and VPD were also explored. In the production approach, crop yield was specified as a function of weather inputs (temperature and precipitation). The results showed that the time when the lowest and highest yields were obtained differed by crops. The highest (43.50 kg/ha) and lowest (1.085kg/ha) yields for cassava were observed in 1999 and 2001, respectively, while both highest and lowest yields for sorghum were recorded in 2012. Daily maximum temperature between 30 and 35 °C occurred more than a 1000 times over all the days covered in this study (January 1, 1991 to December 31, 2012). The regression results showed that high damage to cassava, cotton and maize was evident by the strong and negative coefficient of Harmful Degree Days (HDD). For sorghum and rice, an exposure to heat range showed a negative influence on the yield. In order to address the negative weather effects and other problems associated with the National Agricultural Insurance Corporation (NAIC) such as little access by farmers, high information asymmetric and transaction costs, crop insurance based on indices from Nigeria Meteorological Agency (NIMET) could be adopted to compensate part of the damage caused to the farm products.

Projection of meteorological droughts in Nigeria during growing seasons under climate change scenarios

“…This sector, however, is significantly affected by climate change, and the impact could be severe in future than present anticipation. Many studies already reported the impact of climate change on agricultural productivity in the country [102][103][104] . Crop simulation models 105 indicated that even an increased rainfall in many parts of Nigeria, there is no likelihood of offsetting expected crop yield reduction due to an increase in temperature, in particular over the medium-term period (until 2050), especially for cereals.…”

Factors Affecting Yield of Crops

“…For example, drought followed by intense rain can increase the flooding potential, thereby creating conditions that favor fungal infestations of leaves, roots and tuber crops. In addition, reduction of bees' density due to global climate change has led to local extinction of several plant species [12]. The production of enough food to match population growth while preserving the environment is a key challenge, especially in the face of climate change.…”

Optimizing Traditional Cropping Systems Under Climate Change: A Case of Maize Landraces and Bambara Groundnut

“…This could be attributed to a reduction in the lower quartile values (Figure 10), which would suggest an increase in maize landrace yield gap with later planting. According to several research outputs, climate change is expected to reduce the length of the growing season and increase the occurrence of dry spells (Mitchell et al, 2015;Ajetomobi, 2016;Paff and Asseng, 2018). Despite the loss of growing days, our result suggests that, when planting on the same day, early planting (September) may ensure stable yields and WUE are obtained.…”