A relay cropping system of cowpea and sweet potato has the potential to improve nutrient availability to sweet potato through biological fixation. A field study was conducted at Gokwe South communal area of Midlands Province in Zimbabwe, during 2015-2016 season under rain fed condition to compare the effects of relay cropping sweet potato (Ipomoea batatas) and cow peas (Vigna unguiculata) on the productivity of both crops. The experiment was laid in a randomized complete block design with six treatments, replicated four times. The treatments (T) were; pure standard fertilized sweet potato (T1), sweet potato + 1 row cow peas (T2), sweet potato + 2 rows cow peas (T3), unfertilized pure sweet potato (T4), (T5) pure 1 row cow peas and Pure 2 rows cow peas (T6). There were significant (p<0.05) vine length differences among the treatments at 3WAP, 5WAP, 7WAP and 9WAP (p < 0.05). Number of vines at harvesting were significantly different (p<0.05) among the treatments. The yield for pure standard fertilized sweet potato was greater than that for sweet potato with +1 rows cowpea, sweet potato +2 rows cowpea and unfertilized pure sweet potato (LSD=0.3706). LER for the sweet potato cowpea inter crop was 1.34, showing an advantage for sweet potato +1 row cow pea inter crop over the two pure crops. The LER for the sweet potato + 2 rows cow pea was 0.388 showing a disadvantage of sweet potato + 2 rows cow peas. The sweet potato +1 row cow pea relay crop had a comparable growth development and yield with the pure standard fertilized sweet potato crop and, had a 34 % advantage over the pure sweet potato and cow pea crop and should recommended in the study area to improve food security.

Keywords: relay cropping pure sweet potato crop pure cowpea crop food security