Nitrogen Recovery and Utilisation Efficiencies for Biomass and Fruit Production in Pepper (Capsicum annum L.) As Affected by Fertilizer Management Strategies/Methods in a Humid Zone of Nigeria

摘要

In recent years, there has been increased tendency for intensive vegetable production in the tropics and the success of this effort depends strongly on the high application rates of fertilizers to maximise yields. However, in addition to high costs of mineral fertilizer and other logistic problems, intensive vegetable production is constrained by high rate of soil fertility depletion, a bane of continuous cropping systems. Capsicum species are high-value vegetable crops and are also important for human nutrition due to their high nutritional contents. The response of pepper Capsicum annum (var. Tatase) to sources of nutrients (nitrogen) and frequency of application (phase application) was analysed in terms of efficiencies of N recovery (uptake) and utilization for shoot biomass and fruit yield (fruit set efficiency) 2004 and 2005 on the field in Akure, a rainforest zone of Nigeria. The aims were to assess the effects of fertilizer materials management on the efficiencies of N uptake and utilisation for fruit setting and fruit yield in pepper. The effects of fertilizer type and frequency of application were significant (p<0.05) on growth and fruit yield of pepper. Single and phase application of the fertilizers strongly influenced soil N status and produced differences in pepper growth and fruit yield characters. Over organic fertilizer and control, NPK and FYM + stubble produced significant increases in the dry weights of root (17, 15%; 17.5, 16%) and shoot (15, 16%; 13, 18%), leaf area (16, 13%; 18, 16%) and fruit fresh weight (42, 54%; 40, 20%), respectively. NPK under single and split application maintained uniformly high level of fruit yields than other treatments. Split application of all fertilizer types enhanced leaf area, root and shoot biomass and fruit yields. Source of N and split application (placement methods) significantly improved N recovery and overall N use efficiency. The improvements in pepper growth and yield characters produced under FYM alone and FYM plus plant debris were accompanied by enhanced efficiencies of N fertilizer recovery (uptake), Nitrogen Harvest Index (NHI) and the utilization of N acquired for shoot biomass and fruit production. Residual N in the soil was high under phase application for fertilizer types (organic and mineral) especially for FYM alone and FYM + stubbles. The differences obtained in residual soil N under the different fertilizers and frequency of application could indicate changing availability of soil N as affected by mineralisation rates of the fertilizers. The status of available soil N enhanced ability of pepper to retrieve soil N. Low residual N and hence superior uptake efficiency were recorded under mineral NPK and organic fertilizer compared with FYM application. High residual N was recorded under phase application, the decreases in soil N in plots on which fertilizer was applied once (single application) could indicate more efficient retrieval of soil N from these plots. Agronomic indices used as measure (parameters for estimation of) N use efficiency were computed. These parameters were strongly influenced by fertilizer management strategy adopted in this study. PEN (physiological N use efficiency), AEN (Agronomic Efficiency). Increamental yield that results from N application (Agronomic Efficiency, AEN) increased under phase application of fertilizer types. Although differences in the estimated REN appear small, it has large implications in terms of cost savings from reduced fertilizer use (procurement and application) could be attained.