Effect of Land Clearing and Tillage Methods on reduced weed incidence and growth and yield of maize-cassava intercrop

Abstract

Agricultural activities have been identified as the most common causes of land transformation. Such transformation results in changes in ecological features, such as weed flora succession. It is in view of this that a work is carried out to evaluate the effect of land clearing and tillage methods on weed incidence under maize - cassava intercropping system. The experiment was carried out at the International Board for Soil Research and Management experimental site, Epemakinde Nigeria. (40 45 0 E, 60 450 N) after three cropping years. The treatments consist of three land clearing methods thus, given a split plot fitted into Randomized complete block design (RCMD) in which case the three land clearing methods: Slash and burn (SB), bulldozed not windrowed (BNW) and bulldozed windrowed (BW) are the main treatments while the four tillage methods namely (zero, conventional, traditional and minimum tillage) constituted the sub- treatments. Data were generated on maize and cassava morphological characteristics as well as weed incidence at 6 and 16 weeks after planting (WAP). The result indicates BW and BNW had more grain yield (2.66 tha-1and 2.65 tha-1) respectively, on the average representing 5.1% and 4.7% increase in yield above slash and burn (2.53tha-1). Traditional and minimum tillage had more grain (2.94 and 2.59 tha-1) on the average which represents 22.5% and 7.9% increase in yield above convectional tillage (2.40 tha-1). Cassava fresh weight was significantly (p<0.05) affected by the land clearing methods, with SB and BNW (21.94 and 21.20 tha-1) having higher yields than BW on the average. This represents 44.1% and 39.2% increase in cassava fresh weight above bulldozed windrowed (15.23 tha-1). Weed coverage at both 6 WAP and 16 WAP showed no significant difference (p>0.05) among the land clearing treatments, although slash and burn had the least weed coverage (55.5%) on the average representing 9.2% and 8.9% lower than those of bulldozed windrowed (60.63%) and bulldozed not windrowed (60.46%). Zero tillage and traditional practices had the highest weed coverage of 86.11% and 82.17% respectively, representing 207.5% and 193.5% increase over conventional tillage (28.00%). In conclusion, slash and burn under minimum tillage treatment, which gave a better maize and cassava yield as well as reduced weed problem, appears a better option.