AGRONOMIC AND ECONOMIC EVALUATION OF PYMARC ON MAIZ E YIELD IN RIFT VALLEY PROVINCE OF KENYA
MetadataShow full item record
On many smallholder farms in Kenya, organic materia ls such as animal manures are commonly used to replenish soil fertility. These soil amend ments are however, in short supply and are unlikely to meet the nutrient requirements of crops over large areas. There is need, therefore, to explore other n on- traditional organic inputs as sources of crop nutri ents. One such organic resource is pyrethrum marc (pymarc), a by-product of pyrethrum processing. The researchers investigated the effect of rate and me thod of pymarc application i.e. spot-applied (SP) or bro adcast (BR) on maize yields and conducted economic analysis using partial budgeting to determine its p otential for adoption for two consecutive seasons a t three sites in the Rift Valley Province. The treatments c onsisted of two methods of pymarc application (SP a nd BR) in a factorial combination with two rates of py marc i.e. 4 and 8 t ha -1 laid down in a randomized complete block design. There was no significant int eraction between the method and rate of pymarc application. There was also no significant effect o f pymarc application method but maize yields increa sed with increasing rate of pymarc application which wa s attributed mainly to increased soil phosphorus availability. Net financial benefits were, however, negative for all treatments in all seasons, theref ore, casting doubts on pymarc’s potential for adoption a s a soil fertility management intervention. Key Words: Pymarc, Methods of application, Maize yi eld and Partial budgeting. Introduction Soil fertility depletion due to continuous cultivat ion with little or no nutrient inputs is a major co nstraint to crop production in many parts of Kenya. Nitrogen an d phosphorus are usually the most limiting nutrient s for crop production and their deficiencies often oc cur simultaneously on many farms (Jama et al., 1997 ). On smallholder farms, organic materials are commonly u sed as sources of nutrients. In most cases the orga nic materials are often treated as sources of N (Palm e t al., 1997) with little attention given to their p otential to provide P to crops. Furthermore, most research on o rganic inputs in Kenya has focused on the tradition al organic amendments such as animal and green manures . It is now, however, clear that these amendments are in short supply and are unlikely to meet the nu trient requirements of crops over large areas. Ther e is need, therefore, to explore other non-traditional o rganic inputs as sources of crop nutrients. One suc h organic resource is pymarc, a by-product of pyrethr um processing. One ton of dry pyrethrum flowers yie lds about 970 kg of pymarc of which less than 10% is us ed as animal feed (Muriuki et al., 2001). The surpl us is often left to waste. Pymarc has average N, P, and K contents of 2.2, 0.2 8 and 3.8% respectively, and is therefore a relativ ely rich source of these nutrients (Muriuki et al., 200 1). However, while the nutrient concentration may b e a good indicator of the potential of an organic resou rce to supply nutrients to crops, plant growth is u sually the best way of determining the effectiveness of an organic material as a nutrient source. The rate an d method of application are important factors that de termine the effectiveness of a nutrient source. The two also impact on profitability, which usually determi nes whether or not a technology will be adopted. The two common methods of application of nutrients are spot placement (SP) and broadcast application (BR). SP of pymarc may concentrate the nutrients cl ose to the plant roots and therefore make it more effective than BR. However, given the powdery natur e of pymarc, SP may also reduce the surface area of the pymarc in contact with the soil thus slowing do wn microbial degradation and hence nutrient release . While BR increases contact between the pymarc and t he soil thus increasing microbial degradation of th e organic material, the thin spreading may result in a dilution effect whereby the effective amounts of nutrients available to plants are greatly reduced. The agronomic effectiveness of the two application methods notwithstanding, SP is usually more labor i ntensive than BR and the choice of the application Volume 2: Issue1, 2009 Int.j. disaster manag.risk. reduct. ISSN: 1992-2744 2 method should therefore be based on economic consid erations (Opala et al., 2007). Unfortunately, economic analysis is rare in agronomic studies thus limiting the farmers’ ability to make informed cho ices. High rates of nutrient application usually lead to high yields. Most studies have however often used unrealistically high organic input rates, such as 1 0 t ha -1 , that are unlikely to be used by farmers. There is therefore merit in testing the effectiveness of org anic inputs at rates that are likely to be used by farmers. The objectives of this study were to determine the (i) effects of rate and method of pymarc application i.e. spot-applied or broadcast on the yield of maize (ii ) the economic returns of using pymarc on maize.