Year: 2026 | Month: June | Volume 13 | Issue 1
Nitrogen Rates Affect the Growth and Yield of Pearl Millet and Sorghum in Kiambu and Bomet Counties, Kenya
Drusilla Cherono
Mwende Ngie
James Mutegi and Joseph Gweyi-Onyango
DOI:10.30954/2347-9655.01.2026.6
Abstract :
Sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) play a vital role in food security and as livestock feed in arid and semi-arid regions due to their drought tolerance, early maturity, and low nutrient requirements. Despite their importance, yields in parts of Kenya remain low, largely due to sub-optimal nitrogen (N) management. This study assessed the effects of four nitrogen levels (0, 40, 80, and 120 kg N ha-1) on the growth and yield of pearl millet and sorghum in Kiambu and Bomet Counties. A randomized complete block design with split plots was used, with crop species (sorghum and pearl millet) as main plots and nitrogen rates as subplots. The treatments were replicated three times. Data on plant height, tiller number, and grain yields were collected. Results showed a significant difference (p < 0.05) across nitrogen rates, crop species, and locations. Application of 120 kg N ha-1 produced the tallest plants (163.7 cm in Kiambu and 168.7 cm in Bomet at Flowering). Pearl millet produced more tillers (up to 13 per plant) than sorghum at high nitrogen rates. Grain yield increased consistently with nitrogen application, with 120 kg N ha -1 giving the highest yield at both sites. Interestingly, the yields for both sorghum and pearl millet were higher in Kiambu (KU) than in Bomet when not supplied with nitrogen fertilizers with yield differences for pearl millet between the two sites being 69% while the differences for the two sites for sorghum being 59%. The difference between non-fertilized treatment and highest N (120 kg ha-1) for pearl millet in Bomet was 31 folds while for KU it was 13 folds. Conversely, yield differences between control and highest dose at Bomet was 30 folds for sorghum and 14 folds at KU. The impact of N fertilizer was tremendous in Bomet site as compared to Bomet site. These findings demonstrate that nitrogen availability strongly enhances the vegetative growth and yield potential of both crops but this is strongly dependent on the site and growth stages of growth. Both crops are adoptable to low N with Sorghum being suited to low N than while pearl millet. The study concludes that despite these crops being considered orphan crops, their demand for N is particularly higher than initially assumed and that 120 Kg ha-1 was not the optimal amount.
Highlights
- With climate change and burgeoning populations, more crop production with shift to Arid and Semi-Arid frontier with fragile conditions.
- Both Sorghum and Pearl millets have been considered to be orphan crops in Kenya and have been grown by smallholder farmers with low N fertilizations.
- The results show a linear increase in grain yields of both sorghum and pearl with increasing N without reaching the optimal level with minimal the amounts in the study.
- The study underscores the need for fertilizing these crops with N to avoid soil mining.
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