Performance of Cassava on Soil Amended with Spent Mushroom Substrate Under Varying Levels of Tractor Compaction

Cassava is an important and most widely consumed staple food in Southern Nigeria. However, its production especially in South-South, Nigeria, is mainly at the subsistence level. In order to boost production, mechanized farming and the use of fertilizers have always been advocated. Mechanized farming, however, involves the use of tractors that compact the soil. This study was therefore conducted to investigate the performance of cassava (manihot esculenta) on a sandy loam soil amended with spent mushroom substrate (SMS) under varying tractor passes, at the Institute of Agricultural Research and Training, Rivers State University, Port Harcourt, Nigeria. 92kg of SMS was mixed with the soil, ploughed and harrowed using a tractor. At the end of these operations, the tractor was allowed to run on the experimental plots without any hitched implement so as to compact the soil using 0, 2, and 4 tractor passes (0TP, 2TP and 4TP). The compaction levels arising from the several tractor passes were measured with a cone penetrometer. A similar plot of land which neither had SMS nor tractor passes was included as a control (C) making it a total of four Treatments in all. The randomized complete block design with three replications was used in establishing the experiment. Two cassava stems were planted per stand in each plot, at a spacing of 1m x 1m, with supplemental irrigation applied at a rate of 0.002m^3/s. The plant parameters measured were emergence rate, plant height, stem girth, and yield. The results showed that at 19 days after planting (19 DAP), the emergence rates were 100%, 100%, 42.8% and 28.6% for C, 0TP, 2TP and 4TP respectively. The highest average plant height was obtained from 0TP, followed by C, 2TP and 4TP in that order. The stem girth and yield also followed the same trend. On the whole, the highest mean yield (8833kg/ha) was obtained from 0TP, while mean yields from C, 2TP and 4TP were 8692kg/ha, 8292kg/ha and 4250kg/ha respectively. There was no significant difference between the plant growth parameters and yield at 5 % level. However, for stem girth, there was significant difference at the 5% level between 0TP and 2TP, 0TP and 4TP, and C and 4TP. Also, OTP and 4TP, and C and 4TP of the yield were significantly different at 5%. The results, however, suggest that the level of compaction arising from the number of tractor passes contributes significantly to the performance of cassava planted on sandy loam soil amended with SMS.