Field trials were made to estimate the effect of NPK 15:15:15 fertilizer on the growth and yield of maize were conducted over a two year period. NPK fertilizer applications significantly increase plant height, stem girth, number of leaves, leaf area, leaf area index, dry matter accumulation and yield. The optimum level of NPK 15:15:15 fertilizer for successful production of maize grains was 400 (60 kg N + 27.16 kg P + 49.80 kg K) kg / ha compound fertilizer based on the fact that it had the greatest dry cob yield (12.44 t / ha), grain yield (7.95 t /ha), relative grain yield (2.26) and 100-seeds weight (11.62 g).

The choice of appropriate plant spacing that gives optimum density of sweet potato (Ipomoea batatas (L.) Lam) is crucial for its productivity, considering that plant density of cover crops affects above-ground access to sunlight, degree of soil surface cover, and below-ground tuberization.

A field trial was conducted at the Experimental Farm of the University of Benin, Benin City, Nigeria between May and July in both 2015 and 2016 to evaluate growth and yield responses of cucumber (Cucumis sativum L.) to different nitrogen levels of goat manure. The experiment was laid out in a randomized complete block design involving five treatments and replicated three times. The treatments were cured goat manure applied at levels of 0, 100, 200, 300 and 400 kg N ha-1. Growth parameters were collected on vine length (cm), vine girth (cm), number of branches, number of leaves and leaf area index (LAI). Yield parameters assessed were fruit length (cm), fruit girth (cm), number of fruits per plant and fruit yield (t ha-1). Goat manure application significantly (P < 0.05) influenced growth parameters positively, which led to the enhancement of the fruit yield. Goat manure application levels of 200 (20.85 t ha-1), 300 (20.85 t ha-1) and 400 (26.21 t ha-1) kg N ha-1 had similar (P > 0.05) fruit yield, but significantly (P < 0.05) higher than those of 0 (12.34 t ha-1) and 10 (16.96 t ha-1) kg N ha-1. It thus recommended that goat manure at 20 kg N ha-1 is more appropriate for cucumber production in the humid ultisols environment.

Studies were conducted in 2005 and 2006 at Irrua, Nigeria, to determine the performance of various sizes of minisetts of Dioscorea rotundata cv. ‘Obiaoturugo’ evaluated for size and yield of yield matter and seed yams. These trials involved a macrosett (250 g) and six minisett sizes (25, 30, 35, 40, 45 and 50 g) in a randomised block design with four replicates. The results indicated that larger minisetts had higher degree of field establishment, foliation, leaf area index, total dry weight, percentage of leaf dry matter and net assimilation rate. These growth parameters influenced higher crop growth rate, which was responsible for higher fresh tuber yield. The macrosett’s fresh tuber yield was the greatest (20.48 t ha−1) but had the least multiplication ratio (8.19). The greatest multiplication ratio was obtained from 30‐g setts.

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