# Effect of Zinc-fertilizer on varietal performance of finger millet (Eleusine coracana) and soybean (Glycine max) in western Kenya

## TL;DR

Adding zinc fertilizer with other nutrients improves finger millet and soybean yields and profitability in western Kenya.

## Contribution

Demonstrates that low-dose zinc application boosts crop yields and profitability in zinc-deficient soils.

## Key findings

- Zinc application increased grain yields, zinc concentration, and uptake in finger millet and soybean.
- Low-dose zinc (1.5 kg/ha) provided the highest agronomic efficiency for both crops.
- Zinc application was profitable for farmers in Bungoma and Siaya Counties.

## Abstract

Soil zinc deficiency in Sub-Saharan Africa (SSA) is a major contributor to poor crop responses to nitrogen, phosphorus and potassium (N, P and K) fertilizer leading to low economic returns on fertilizer use. Despite being drought-tolerant crops, finger millet (Eleusine coracana) and soybean (Glycine max) yields are consistently lower than 1000 kg ha−1 in western Kenya. On-farm trials were conducted in Bungoma and Siaya Counties of western Kenya during two subsequent cropping seasons (long & short rains of 2019) to evaluate the responses of two varieties of finger millet (U15 and SEC915) and soybean (SB19 and SB134) to N, P and K after addition of Zn. Zinc was applied at 0, 1.5, and 3 kg ha−1 and N, P and K at blanket rates. Results showed that application of Zn fertilizer alongside N, P and K fertilizer significantly (p < 0.05) increased grain yields, grain Zn concentration and grain Zn uptake. The largest Zn agronomic efficiency (AEZn) was realized when Zn was applied at 1.5 kg ha−1 for both crops. Application of Zn was profitable (VCR >1) for growing finger millet and soybean in Bungoma and Siaya during long rains and short rains. We recommend applying Zn along with N, P and K fertilizer in Zn-depleted soils to increase finger millet and soybean yields.

•Improved finger millet and soybean grain yields were obtained when applying Zn alongside N, P and K fertilizer.•Agronomic efficiency in both finger millet and soybean was largest when Zn was applied at a low level.•Zinc application is required to enrich grain Zn concentration and uptake in Zn-deficient soils for improved nutrition.•Investing in Zn for growing finger millet and soybean was profitable (VCR >1).

Improved finger millet and soybean grain yields were obtained when applying Zn alongside N, P and K fertilizer.

Agronomic efficiency in both finger millet and soybean was largest when Zn was applied at a low level.

Zinc application is required to enrich grain Zn concentration and uptake in Zn-deficient soils for improved nutrition.

Investing in Zn for growing finger millet and soybean was profitable (VCR >1).