Integrated soil fertility management options to improve the production of Amaranthus sp. and Cleome gynandra in subtropical conditions

Amaranthus sp and Cleome gynandra are leafy indigenous vegetables that possess nutritional qualities essential in improving nutrition and food security in the face of climate change. The lack of sustainable fertility guidelines partially hinders their production and promotion. Integrated soil fertility management is a sustainable solution that may improve production and meet the increasing demand. The study evaluated the effects of integrating cattle manure (M) and mineral nitrogen (N) rates on growth of Amaranthus sp. and Cleome gynandra . Six treatments, control, M at 10 t ha ^− 1 , 30 kg N ha ^− 1 (30N), 60 kg N ha ^− 1 (60N), M + 30N and M + 60N were tested in a randomised complete block design replicated thrice. M + 60N produced the most fresh biomass in season 3 (22 211.03 kg ha ^− 1 Amaranthus sp and 14 561.06 kg ha ^− 1 Cleome gynandra ) whereas treatment M + 30N produced the highest seed yield of Amaranthus sp and Cleome gynandra (7 101.64 kg ha ^− 1 and 5 270.81 kg ha ^− 1 respectively). There was a positive synergy between integrating organic and mineral N (M + 30N and M + 60N) on growth, particularly in the later seasons underscoring the cumulative benefits of nutrient residual effects. M + 30N offers a more economically and sustainable option as yields and growth parameters were not significantly different from M + 60N treatment. The study advances that integrating cattle manure and mineral nitrogen fertilizers is a sustainable fertility strategy for intensifying Amaranthus sp and Cleome gynandra production in subtropical conditions.