Okra contributes an important part of the diet to many people in the tropics, more especially in Cameroon. But its production is seriously affected by poor soil fertility. In other to mitigate this problem, a field experiment was conducted from April to august 2016 at Institute of Agricultural Research for Development (IRAD) Nkolbisson-Yaoundé with the main objective to evaluate the effects of different soil amendments on the performance of okra (Abelmoschus esculentus L.) crop. The experiment was laid out using a randomized complete block design (RCBD) with three replications and eleven treatments: (Tithonia leaves (6700 kg/ha), piggery manure (6700 kg/ha), foliar fertilizer (0.6 kg/ha), urea (200 kg/ha), NPK20-10-10 (200 kg/ha), Tithonia leaves (3350 kg/unit) + NPK20-10-10 (100 kg/unit), Tithonia leaves (3350 kg/unit) + Urea (100 kg/ha), urea (100 kg/ha) + NPK 20-10-10(100 kg/ha), Tithonia leaves (100kg/ha) + foliar fertilizer (0.3 L/ha), Tithonia leaves (3350 kg/ha) + piggery manure (3350 kg/ha) and control (0 kg/ha). The Results showed that the growth and yield of okra were significantly (P<0.05) affected by different soil amendments. The number of days to achieve 50% shoot set was significantly (P<0.05) greater (50.66±1.24) with the use of NPK 20-10-10 as compared to the rest of the treatments. The number of days to achieve 50% flowering was significantly (P<0.05) greater (59.33±1.46) with the use of Tithonia leaves as compared to the rest of the treatments. The tallest plants and highest number of fruits per plant were recorded from the urea treatment, while the use of foliar fertilizer resulted in many branches and leaves per plant. A combination of NPK and Tithonia leaves resulted in heavy fruits per plant. NPK treatments produced the highest number of fruits and the heaviest fruits as compared to the foliar and control treatments. From the results obtained, it can be concluded that the application of foliar fertilizer, urea and NPK 20-10-10 + Tithonia and NPK which recorded the highest growth and yield parameters among all the treatments are the best treatments and should be adopted by farmers in the study area to maximize their yields. However, further studies on other combinations of organic fertilizers need to be carried out in different areas in order to come out with desired new alternatives that will reduce the use of high quantity of inorganic fertilizers.

Soil acidity, combined with high aluminum toxicity, is one of the major problems limiting agricultural productivity. The objective of this work was to improve growth and yields of okra on acidic and degraded soil in the Center region, Cameroon, using an innovative fertilization approach and lime material. The soil is ferralitic, very acidic, with aluminum toxicity and significant imbalance in the (Ca/Mg/K) ratio of (55/15/30). Seven fertilization treatments were applied: Control without fertilizer; arbuscular mycorrhizal fungi (AMF); AMF+50% poultry manure (AMF+½ PM); mineral fertilizers with cation balance at 100% (MF100 %); AMF+50% mineral fertilizers (AMF+50 % MF); poultry manure at 50%+50 % mineral fertilizers (MF50%+½ PM) and poultry manure (PM). Two varieties of okra were used (Kirikou F1 and Local). The experimental design was a split-plot with two factors. Considering MF, an innovative Ca/Mg/K ratio of 68/23/9 was applied. The results showed that the applied fertilizers had a significant effect on the agronomic parameters of okra with MF50%+½ PM followed by PM and MF100% as the best treatments. An average increase in fresh yield from 111% to 1840% over the control was recorded and the best symbiotic parameters were observed at the AMF treatment associated with the Local variety. This variety responds better to organic matter intake while Kirikou F1 is more favorable to chemical fertilizer addition.