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Weed infestation is among the primary reasons for low yields of soybean in Nigeria and other parts of Sub Saharan Africa (SSA). Field trials were therefore carried out in 2016 and 2017 cropping seasons to evaluate the effect of row spacing and weed management methods on growth and yield of soybean. The use of 50 cm row spacing resulted in significant (P < 0.05) reduction in weed cover score, weed density and weed dry matter with subsequent increase in soybean growth and grain yield compared to 75 and 100 cm row spacings in both years. In addition, early weed control with probaben at 2.0 kg a.i (active ingredient) ha1 followed by (fb) supplementary hoe weeding (shw) at 6 weeks after sowing (WAS) suppressed weeds and increased soybean growth, which carried through to final dry matter and yield. Pre-emergence application of Probaben fb shw at 6 WAS gave the best weed control and resulted in significantly (P < 0.05) higher soybean grain yield compared to two and three hoe weedings or sole application of probaben under 50 and 75 cm inter-row spacing. However, three hoe weedings gave the best weed control and grain yield under 100 cm inter-row spacing. These results suggest that narrow row spacing of 50 cm and weed control by pre-emergence application of probaben fb shw will improve the productivity of soybean. Wide row spacing, however, required longer weed-free period and consequently multiple hoe weeding for optimum soybean yield.

Weed infestation and inherent low soil fertility are among the major factors attributed to the low yield of rice in Nigeria. Field trials were therefore conducted to evaluate the effect of nitrogen application levels and weed control methods on growth and yield of upland rice (var. NERICA 2) at the Teaching and Research Farm of the Federal University of Agriculture, Abeokuta (07o 15?N, 03o 25?E) during 2015 and 2016 cropping seasons. Three nitrogen (N) levels (0, 60 and 90 kg/ha) were evaluated and they constituted the main plot treatments, while three weed control treatments, viz: pre-emergence application of Orizo Plus? (propanil plus 2, 4-D) at 2.0 kg a.i ha-1, Orizo Plus? at 2.0 kg a.i ha-1 followed by supplementary hoe weeding (SHW) at 6 weeks after sowing (WAS) and three hoe-weeding regimes at 3, 6 and 9 WAS, and a weedy check constituted the sub-plot treatments. All the treatments in different combinations were laid out in a randomized complete block design with a split-plot arrangement with three replicates. Results indicated a significant (p?0.05) increase in weed density and dry matter with an increase in N application level from 0 to 90 kg ha-1. Similarly, crop vigour and plant height increased significantly (p?0.05) with increasing N application levels up to 90 kg ha-1. However, 60 and 90 kg N ha-1 were at par in increasing the number of tillers, leaf area index and yield attributes of rice. All the weed control methods resulted in a significant (p?0.05) reduction in weed density and dry matter with subsequent increase in rice growth and yield than the weedy check. Pre-emergence application of Orizo Plus? followed by SHW at 6 WAS and three hoe-weeding regimes resulted in significantly (p?0.05) lower weed density and dry matter, and a higher number of tillers, panicle weight and grain yield than a sole application of Orizo Plus?. With Orizo Plus? followed by one SHW or three hoe-weeding regimes, increasing N application levels resulted in a significant (p?0.05) increase in grain yield of rice. However, with Orizo Plus? applied alone, increasing N application levels did not increase rice grain yield. These results suggest that Orizo Plus? at 2.0 kg a.iha-1 followed by one SHW at 6 WAS integrated with N application at 90 kg ha-1 is adequate to effectively control weeds and increase rice yield in the rainforest-savannah transition zone of Nigeria.

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The high cost of cultivation and weed management are major limiting factors to increasing soybean productivity and net returns. Field experiments were conducted in 2016 and 2017 at the Teaching and Research Farm of the Federal University of Agriculture, Abeokuta to evaluate the economic performance of different row spacings and integrated weed management system in soybean. Three row spacings (50, 75 and 100 cm) as the main plots and six weed control methods and a weedy check as sub-plot treatments were accommodated in a split-plot arrangement of a randomized complete block design with three replications. There was a significant reduction in weed biomass with a reduction in row spacing from 100 cm to 75 cm and 50 cm. Furthermore, the cost of production, grain yield and gross profit increased with a reduction in row spacing from 100 to 75 and 50. When soybean was sown at 50-cm row spacing, the application of Probaben 400EC (metolachlor 20% w/v + prometryn 20% w/v) or Butachlor 60EC (butachlor) at 2.0 kg a.i/ha each followed by supplementary hoe-weeding at 6 weeks after sowing (WAS) resulted in the highest yield of 2301-2484 kg/ha and total revenue of 2129-1972 $/ha. Conversely, three hoe-weedings resulted in the highest yield of 2155-2081 kg/ha and total revenue of 1848-1783 $/ha for crops grown at 75-and 100-cm row spacings. Despite the higher yield and revenue obtained with three hoe-weedings for crops grown at 75-and 100-cm row spacings, the gross profit and benefit-cost ratios obtained were lower than those obtained with herbicide treatments applied alone or followed by supplementary hoeweeding. In terms of profitability, soybean planted at 50-cm row spacing and treated with Probaben 400EC at 2.0 kg a.i/ha followed by supplementary hoeweeding gave the highest gross profit of 1479 $/ha. Two or three hoe-weedings in soybean planted at narrow-row (50 cm) spacing did not guarantee the highest yield, but rather increased the cost of weed control. This study suggests that narrow-row spacing (50 cm) and pre-emergence herbicides will help to reduce the number of