Transmission and storage properties of a tropical loamy sand soil as influenced by organic-based and inorganic fertilizers

Short-term effect of organic and inorganic amendments on soil physical quality (SPQ) is marked when dealing with tropical soils which are naturally exposed to a high risk of water erosion. This study assessed the suitability of Tithonia diversifolia (Mexican Sunflower) when incorporated as green manure (GM) and also composted with poultry manure (PM) and other organic-based and inorganic fertilizers to improve some hydraulic properties of an Alfisol subject to excessive drainage. Treatments applied include fresh T. diversifolia (GM), PM, T. diversifolia composted with PM, organo-mineral fertilizers (OMF), neem fertilizer (NF), inorganic fertilizer (20-10-10 NPK), and control in a randomized complete block design and replicated four times. Soil samples were collected at 0-20 cm depth to determine near steady-state infiltration rates (I-s), sorptivity, transmissivity, saturated hydraulic conductivity (K-s), macroporosity (MacP), microporosity (MicP), air capacity (AC), and relative water capacity (RWC). The I-s rates were significantly (P <= 0.05) reduced to optimum range with the addition of the organic fertilizers over very high value (128.7 cm hr(-1)) observed for control. Whereas, K-s was enhanced in the order: GM > compost (CP) > NF > inorganic fertilizer > control > organo-mineral fertilizer > PM. Sorptivity and transmissivity were highest in control and inorganic fertilizer plots, indicating that the addition of organic fertilizers lowered these parameters while MacP, MicP, AC, and RWC were generally increased with the addition of organic-based and inorganic fertilizers. Specifically, NF increased MicP by 34% over control. Values for RWC which were within the optimum range (0.60-0.70) were only obtained with NF (0.74), OMF (0.72), NPK (0.70), and GM (0.60). The SPQ parameters assessed in this study were enhanced by the addition of fresh T. diversifolia applied as GM and CP compared to other treatments. Therefore, T. diversifolia usually burned by farmers should instead be incorporated into the soil as manure.