Identification of a sustainable integrated soil fertility management option in the tropics will not only salvage the degraded soils but also enhances the attainment of the goal of food security. This study was conducted in 2004 and 2005 on a degraded tropical Alfisol in south western Nigeria to evaluate the effect of legume residue, poultry manure and inorganic fertilizers on maize yield, nutrient uptake and soil properties. The treatments consisted of two rates of poultry manure (0 and 5 t ha -1 ), three rates of N fertilizer (0, 50 and 100 kg N ha -1 applied as urea), three rates of P fertilizer (0, 30 and 60 kg P ha -1 applied as single super phosphate) and two soybean treatments (with or without incorporation of legume residue) in various combinations as a factorial experiment in Randomized Complete Block design with three replicates. Results showed that poultry manure alone led to significant increase in maize yield (60%) and soil organic matter (45%). In contrast, legume residue incorporation gave significantly lower increase in yield (7%) and soil organic matter (11%). However, the combined application of poultry manure and legume incorporation led to 72% increase in maize yield as opposed to 63 and 10% increase recorded when manure alone or legume alone were incorporated, respectively. Optimal maize yield was achieved when manure application was integrated with P fertilizer application. The interaction of P fertilizer and legume incorporation indicated that soil phosphorus and maize P concentration were significantly increased with the application of the P fertilizer and legume incorporation. Hence, the application of P fertilizer alone is most likely to be economical compared with its integration with legume incorporation.

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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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