Sustaining yam yields amidst climate threat in the forest – savannah transition zone of Ghana

Abstract

1516 With about 70% of yam tuber been water, yield is critically affected during bulking as a result 17 of onset of temporal drought. As a consequence of climate change, farmers who are into 18 Dioscorea rotundata (white yam) production for local and international market lose their 19 investments mainly due to erratic precipitation, drought spells culminating into low yields of 20 just 12t/ha compared to the potential of about 22-49t/ha depending on the variety. Innovative 21 land uses technologies with higher and sustained productivity for yam production are 22 imperative. This study verifies improved agronomic package for sustainable yam production 23 in yam growing areas in the forest -savannah transition zone of Ghana during the 2015 and 24 2016 cropping seasons. The improved agronomic package included use of ridging as seedbed, 25 seed treatment before planting, fertilizer application at a rate of 30:30:36 N:P 2 0 5 :K 2 0 kg/ha 26 plus 15 kg/ha Mg and 20 kg/ha S as MgSO 4 and the use of minimum stakes (trellis; 30-50% 27 less number of stakes used by farmers staking). This was compared with farmers' practice 28 which consisted of mounding, no fertilizer application and no seed treatment. The results 29 revealed significant (P ≤ 0.01) yam yields of more than 60% difference between the improved 30 agronomic practice and farmers' practice from Ejura, Atebubu and Kintampo yam growing 31 communities. Adoption of improved agronomic practices does not only sustain yam 32 production and address deforestation but also provide higher returns on investments 33 promoting climate resilience by small holders. Key Words35 Climate smart agriculture, Fertilizer, Improved technology, Seed treatment, Trellis staking, 36 Yam 37 38 Background 39 2 40 In Ghana, crops are already experiencing heat stress, drought spells, several pests and 41 diseases outbreak and shorter growing crop duration as a consequent of the changing climate 42 (1). Thus, a potential catastrophe for smallholder farmers and the millions of people who 43 regularly grow rain-fed full season crops such as yam, cocoyam, rice etc.(2-5). Choices about 44 what to grow are often dictated by the ability of the rainfall regime to support moisture for 45 plant growth (6). One way around this would be to breed for varieties with shorter crop 46 maturity durations or management interventions that build on the resilience of cropping 47 production systems to reduce shocks if the shocks from the climate change cannot be done 48 away with. Evidence suggests that climate smart agriculture can make a contribution to 49 mitigation by supporting more efficient use of fertilizers, weed management and reduced 50 staking options in yam production (1,7,8). 51 Yam, an important staple food crop across West Africa is a major non-traditional export 52 crop in Ghana contributing to about 16% of the National Agricultural Gross Domestic Product 53 (9,10). However, there are a number of challenges that hamper the production and 54 productivity of yam. Predominantly amongst them are; inade...