Farm-level production diversity and child and adolescent nutrition in rural sub-Saharan Africa: a multicountry, longitudinal study.

BACKGROUND: Child malnutrition remains widespread in sub-Saharan Africa, especially in rural areas where many households are involved in subsistence farming. Increasing farm-level production diversity (FPD) is often considered a useful strategy to improve child diets and nutrition, but the empirical evidence is mixed. Most studies have investigated associations between FPD and dietary diversity. We therefore aimed to analyse associations between FPD and child and adolescent nutritional status. METHODS: In this multicountry, longitudinal study, we used representative panel data from four countries in sub-Saharan Africa (Ethiopia, Malawi, Tanzania, and Uganda) to test the hypothesis that higher FPD is positively associated with child and adolescent nutritional status. The data were from the Living Standards Measurement Study-Integrated Surveys on Agriculture collected between 2008 and 2019. We included data from all children and adolescents aged 0-18 years with available anthropometric data who were living in households involved in farming activities for home consumption, market sales, or both. FPD was measured in terms of the number of different crop and livestock species and food groups produced on each farm. Child and adolescent nutritional status was measured in terms of height-for-age Z scores (HAZ). We estimated panel data regression models with correlated random effects to control for confounding factors and time-invariant unobserved heterogeneity. FINDINGS: The total sample size included 50 689 child and adolescent observations. In combined models, with data from all countries included, we found one additional species produced on the farm (crop and livestock combined) was associated with a mean 0·015 SD greater child or adolescent HAZ (p<0·0001). The role of FPD tended to decrease with better market access (in more remote locations mean 0·020 SD [p<0·0001] and in less remote locations mean 0·008 SD [p=0·091]). In individual-country models, the effects were smaller and statistically insignificant in three of the four countries. Livestock diversity had larger positive associations with HAZ than crop diversity (livestock diversity effect on HAZ mean 0·085 SD [p<0·0001] and crop diversity effect on HAZ mean 0·007 SD [p=0·080]). In Tanzania and Uganda, higher crop diversity was negatively associated with child and adolescent HAZ. INTERPRETATION: Our findings suggest that further farm-level diversification is not a suitable general strategy to improve child and adolescent nutrition but might be useful in some situations. Livestock production seems to be conducive for improving child and adolescent nutrition on average. Context-specific approaches need to be developed. FUNDING: None.

A revisit of farm size and productivity: Empirical evidence from a wide range of farm sizes in Nigeria.

The relationship between farm size and productivity has been studied extensively in the agricultural and development economics literature. However, most of the documented evidence in sub-Saharan Africa (SSA) is based on samples of small-scale farms operating 5 ha or less, with very little evidence assessing this relationship over a wider range of farm sizes. This omission is especially important considering the rapid expansion of medium-scale farms in much of Africa. This study examines the farm size-productivity relationship over a range of farms between zero and 40 ha in Nigeria. It also tests whether there is heterogeneity in productivity within medium-scale farms depending on how they came into being. Using four measures of productivity, empirical estimates reveal a U-shaped relationship where the IR holds between zero and about 22 ha, turning positive afterwards. Moreover, when medium-scale farms are distinguished between those who were actively engaged as small-scale farmers and stepped up/expanded their scale of operation and those who were primarily in non-farm employment and later stepped into medium-scale farming, the turning point for farmers who stepped up into medium-scale farming is at 11 ha, in contrast to 22 ha for those who stepped in. Further evidence suggests heterogeneity in productivity within medium-scale farms depending on whether the owner-operators stepped up or stepped into medium-scale farming. These findings imply that policies facilitating smallholders' ability to expand the scale of their activities could contribute substantially to growth in farm productivity, agricultural commercialization and increase in food security in Nigeria, although in most areas only a small proportion of smallholder households are in a position to do this.

The effect of land use change on soil fertility parameters in densely populated areas of Kenya.

The current study seeks to assess sustainability of agricultural land use by identifying the effect of land use change on soil quality using cross-sectional data collected through a household survey among 525 farm households in densely populated areas of Kenya. Soil samples were collected, analyzed and compared across three land use types: undisturbed, semi-disturbed and cultivated. To achieve these objectives, descriptive, Nutrient Index approach and Classification and Regression Tree (CART) analysis methods were used. Results indicate that within a period of five decades, agricultural land use has led to a decline in Total Organic Carbon (-72%), Magnesium (-65%) and Boron (-61%), Iron (-22%) and Total Nitrogen (-15%). The drivers of deterioration identified were cutting across inherent properties such as soil chemical (pH), physical (soil mapping unit) and biological (organic carbon) attributes, farmer practices (agricultural commercialization) and exogenous factors (population density and Agro-ecological zones). The study concludes that indeed conversion of land from natural vegetation is associated with deterioration in soil quality and therefore policy needs to create incentives for the build-up of soil organic matter, replenishment of soil macro and micro nutrients. Blending of commercial fertilizers with targeted micro-nutrients, maintenance of soil conservation techniques and long term fallowing are encouraged.

Can economic and environmental benefits associated with agricultural intensification be sustained at high population densities? A farm level empirical analysis.

Boserup's pioneering theory holds that rising population density can be accompanied by sustainable agricultural intensification. But can this positive relationship be sustained indefinitely, or are there conditions under which rising population density can lead to declining agricultural productivity? This study utilizes survey data on farm households in Kenya and soil samples on their main maize plots to assess whether Boserupian agricultural intensification is sustainable at high population densities. The study employs econometric estimation methods to assess the effect of land management practices and population density on soil quality and then determines the effect of soil quality on crop productivity. Results show evidence of endogenous sustainable agricultural intensification accompanied by improvements in soil quality and crop yields at low population densities. However, as population densities exceed roughly 600 persons/km2, we observe a deterioration in indicators of soil organic and reactive carbon, soil pH, and plant available phosphorous. Deterioration in soil quality leads to binding nutrient constraints associated with reduced crop yield response to inorganic fertilizer application that further reduces crop productivity. These results raise the specter of unsustainable forms of agricultural intensification associated with deteriorating soil capital, and point to the imperative of identifying and implementing effective strategies for increasing farmers' use of sustainable land management practices in rural areas facing already high and rising population densities.