A field experiment was conducted to evaluate the effects of irrigation intervals and phosphorus application rates on grain yield of two cowpea varieties during 2018 and 2019 dry season. The experiment was laid out in a split plot design with three replications. The treatments consist of combinations of 2 cowpea varieties (SAMPEA 14 and 15), 3 irrigation intervals (5, 10 and 15-days) and 3 phosphorus (P) levels (0, 20 and 40kg/ha), respectively. Results indicated that grain yields of  two cowpea varieties were affected (P<0.05) by irrigation intervals and phosphorus application rates during the two years trials and the mean. The shortest irrigation interval produced the least number of pods (NP) per plant (15.11, 16.38 and 15.74) in 2018, 2019 trials and the mean, respectively. The differences in 100-Seed weight (SW) among the irrigation intervals was significant, showing an increasing trend (P<0.05) in order of 15>10>5-day intervals in 2018 and 2019 trial. Similarly, P application rates on NP and number of seeds were significant (P<0.05) during the two years trial and the mean, showing an increasing trend with 40 kg P/ha having higher values than 20 kg P/ha and the control. SAMPEA 14 recorded higher (P<0.05) GY compared to SAMPEA 15 during the two years trial and the combined mean. In the combined mean, 5 day irrigation interval recorded the least Pod yield (PY) of 0.30 t/ha, Grain yield (GY) of 0.22 t/ha and Shelling percentage (79.83 %) compared to 15 days interval. However, the 40 kg P/ha application rate produced more GY compared to 20 kg P/ha and the control during the two years trial and the mean. It is therefore concluded that, farmers should irrigate SAMPEA 14 cowpea variety at every 15 days in combination with 40 kg P/ha application rate for optimum GY yield during the dry season in the northern guinea savannah of Nigeria.

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