EFFECTS OF INTEGRATED APPLICATION OF RHIZOBIUM AND PHOSPHATIC FERTILIZER ON GROWTH, NODULATION AND YIELDS OF SOYBEAN IN MERU SOUTH KENYA

Abstract

The cultivation of soybean is increasing in Kenya due to its widespread use in the food and feed industry. Production is, however, constrained by low soil nitrogen (N) and phosphorus (P) levels. A field trial was conducted at Chuka University Research farm to determine effects of integrated application of rhizobium and phosphatic fertilizer on growth, nodulation and yields of soybean. Treatments included three rates of Triple superphosphate fertilizer (0, 20 and 30 kg^- ha^-1), and three rates of rhizobia (0, 100 and 200 g ha^-1) using two soybean varieties (SB19 and SB24). Each treatment combination was replicated three times in a randomized complete block design in a split plot arrangement and the experiment was repeated once. Data collected included the plant height, number of branches, number and weight of nodules, number of pods, fresh and dry shoot weight and grain yield.  The data was subjected to analysis of variance using SAS statistical programme and significantly different means were separated using Tukey’s Studentized range test. It was observed that rhizobia and phosphatic fertilizer had significant effect (p=0.05) on the plant height, number of nodules, fresh and dry weight of nodules and mean number of branches and pods, fresh and dry weight of shoots and weight of seed plant¹. The overall means for plant heights, nodule number, fresh and dry nodule weights, number of branches and pods, fresh and dry weight of shoots and weight of seeds plant¹ were 29.35 cm and 26.79 cm, 38.71 and 35.14, 0.51 and 0.38, 5.5 g and 12.54g, 49.13 and 59.18, 77.65 and 90.91, 56.99 and 69.33g, 168.9g and 148.13g for SB19 and SB24 respectively. The SB24 genotype remained significantly superior to SB19, with same treatment levels employed. From the results, it can be concluded that integrated application of rhizobia and phosphatic fertilizer (TSP) has significant effect on growth, nodulation and yield of soybean.