Browsing by Author "Godfrey‐Sam‐Aggrey, W."

Now showing 1 - 10 of 10

Bark analysis as a guide to cassava nutrition in Sierra Leone
(Taylor & Francis, 1979) Godfrey‐Sam‐Aggrey, W.
Cassava main stem barks from two experiments in which similar fertilizers were applied directly in a 2 confounded factorial design were analyzed and the bark nutrients used as a guide to cassava nutrition. The application of multiple regression analysis to the respective root yields and bark nutrient concentrations enable nutrient levels and optimum adjusted root yields to be derived. Differences in bark nutrient concentrations reflected soil fertility levels. Bark analysis and the application of multiple regression analysis to root yields and bark nutrients appear to be useful tools for predicting fertilizer recommendations for cassava production.
Effect of potash fertilizer on leaf nutrients and their relationships to tuber yields of sweet potato
(Taylor & Francis, 1977) Godfrey‐Sam‐Aggrey, W.
The fourth, fully‐expanded leaves at sweet potato vine tips were sampled at harvest from two separate but similar experiments on njala upland soils after 7 years bush fallow to study the effects of timing and rates of K fertilizers on leaf nutrients and their relationships to sweet potato tuber yields. Potash showed significant effects on leaf P, leaf Zn, leaf Ca, leaf Mn, leaf K/P and leaf Ca/Mg. K x timing interaction affected leaf K/Mg and leaf K/P but timing of Z application did affect significantly neither leaf nutrients nor leaf nutrient ratios. Significant quadratic effect of K on tuber yields as well as significant cubic K x timing interaction effect on tuber yields were observed. There were significant negative correlations between tuber yields and leaf N and between tuber yields and leaf P, indicating that increases in either leaf N or leaf P depressed yields. On the basis of coefficient of determination, increases in leaf N contributed significantly more to yield variation than increases in leaf P. Analysis of covariance and multiple regression studies showed lack of significance of 10 nutrients on tuber yields. Sweet potato tissue which reflects differential nutrient levels with significant effect on tuber yields must be sought. Apart from the added fertilizer, the total effect of ether factors which affect nutrient status and crop performance must be considered.
Effects of Alar on Growth, Flowering and Yield of Okra
(Cambridge University Press, 1978-04-01) Godfrey‐Sam‐Aggrey, W.
SUMMARY Effects of Alar on growth, flowering and yield parameters of standard-planted and closely-planted late-bearing okra were studied. Lower concentrations of Alar, applied once 6 weeks after sowing on standard-planted okra, significantly advanced days to first flowering and depressed height at first flowering and final height. Higher Alar concentrations, particularly 2000 ppm applied twice after 3 and 6 weeks on closely-planted okra, produced more, longer and heavier pods, and therefore higher total pod yield in unstopped than in stopped okra, in addition to advancing days to first flowering and depressing height at first flowering and final height. The agronomic practice of stopping okra at 6 weeks reduced pod number, pod weight/plant and total pod yield/ha in unsprayed plants.
Effects of Cutting Lengths on Sweet Potato Yields in Sierra Leone
(Cambridge University Press, 1974) Godfrey‐Sam‐Aggrey, W.
SUMMARY Effects of cutting lengths on tuber yields and vine production of Missus and Madam sweet potatoes, as influenced by two different fertilizer regimes, were studied on Njala upland soils of Sierra Leone. Cuttings 61 cm. long gave significantly the highest tuber yields for both early-maturing cultivars when fertilized with 336 kg. sulphate of ammonia, 112 kg. basic slag, 448 kg. sulphate of potash, 841 kg. lime and 340 kg. sulphate of magnesium per ha. in two split applications a month apart. Fertilized with 502 kg./ha. sulphate of ammonia per application for 4 applications, 61 cm. long cuttings again gave the highest vine production. The lower the vine/tuber ratio, the higher the tuber yield.
Effects of Delayed Hand Weeding on Sole-crop Cassava in Sierra Leone
(Cambridge University Press, 1978-07-01) Godfrey‐Sam‐Aggrey, W.
SUMMARY The effects of delayed hand weed control at 30-, 45-, 60-, 90-day intervals, and no weeding, on sole-crop cassava, was studied in two experiments on the upland soils of Sierra Leone. Timing and frequency of weeding were important in influencing root number and root yield, and delayed weed control depressed both attributes. The critical period of competition was in the 45-day weeding interval, with six weedings in a 14-month growing period. Rottboellia exaltata was the predominant species amongst the permanent grasses on the no-weeding plots.
Effects of fertilizer timing and placement on grain yield and leaf nutrients of sole‐crop cowpeas (V. unguiculata) in Sierra Leone
(Taylor & Francis, 1977) Godfrey‐Sam‐Aggrey, W.
Effects of fertilizer timing and placement on the grain yield and leaf nutrients of uninoculated sole‐crop cowpeas in two experiments during the minor cropping season on Njala upland soil of Sierra Leone were studied. Timing and placement and their interaction had no significant effects on grain yield. Placement affected highly significantly lamina Mg, Cu and Co and significantly lamina N and Ca. Placement and timing x placement interaction affected highly significantly petiole N and petiole P respectively. Timing affected highly significantly petiole N, which decreased as fertilizer application was delayed. The spectrum of nutrient distribution in both lamina and petiole was decidedly different. Multiple regression studies indicated that variability in only petiole Mg, Cu and Co significantly contributed to grain yield variability. By the introduction of 15 nutrients (6 lamina and 9 petiole) after examining the linear regression coefficients into a composite multiple regression study, lamina Ca, petiole Fe and petiole Co were selected as significant contributors to grain yield variability with marked improvement in R2. Removal of the effects of the correlated variables produced significances in the effects of fertilizer placement and timing x placement interaction on grain yields.
Effects of Fertilizers on Harvest Time and Yield of Cowpeas (Vigna unguiculata) in Sierra Leone
(Cambridge University Press, 1973-10-01) Godfrey‐Sam‐Aggrey, W.
SUMMARY Effects of fertilizers on harvest time and yield of cowpeas were studied on upland soils in Sierra Leone. In a 25 confounded factorial trial, on soil which had been cropped successively with 2 years of Smooth Cayenne pineapples and 14 months of cassava, the treatments did not affect harvest time significantly, but N, P and NP Mg produced very favourable effects on grain yields. In a randomized complete block experiment on soil previously cropped with two successive cassava crops, there was a significant difference in total yield of dry pods between the control and most treatments.
Effects of Plant Population on Sole-crop Cassava in Sierra Leone
(Cambridge University Press, 1978-07-01) Godfrey‐Sam‐Aggrey, W.
SUMMARY Effects of plant population on mean yield and yield components of 2-year sole cassava crops were studied on Njala upland soils of Sierra Leone in two experiments. Increasing plant population of multi-shoot Cocoa cassava over 7000/ha decreased all the parameters studied except top/root weight ratio, which increased. The observed effects were attributed to competition for environmental resources, since area of land/plant unit decreased as plant population increased. The relations between plant populations and yields of fresh root and cortex dry matter were asymptotic, indicating that the respective yields were products of the vegetative phase of cropping.
Effects of Potash Fertilizers on Sweet Potato in Sierra Leone
(Cambridge University Press, 1976) Godfrey‐Sam‐Aggrey, W.
SUMMARY The effects of frequency of potash fertilizer application and of different rates on sweet potato yields were studied in three different cropping systems on Njala upland soils. Fertilizers containing higher K rates (448 kg/ha sulphate of potash) and an N/K ratio of 3:4, gave maximum tuber and low vine yields with low vine/tuber ratios on intensively cropped areas, whereas fertilizers containing lower K rates (112 kg/ha sulphate of potash) and an N/K ratio of 3:1 gave maximum but relatively low tuber and relatively high vine yields, with relatively high vine/tuber ratios on newly cropped areas after seven years bush fallow. Two equal split applications of fertilizer is recommended under the weather conditions prevailing in this part of Sierra Leone.
Relation of citrus leaf nutrients to internal fruit quality in Sierra Leone
(Taylor & Francis, 1979) Godfrey‐Sam‐Aggrey, W.
In a mineral nutrient survey, fruits from grapefruit, sweet orange and tangerine trees whose leaves were sampled were analysed for internal quality and then correlated with the respective leaf analysis values. Correlations amongst leaf nutrients were also studied. Statistically significant simple correlations were found between some internal quality parameters and certain leaf nutrients. Due to sampling limitations, a multi‐element consideration in the nature of multiple regression studies was not considered thus limiting the utility of the results in evaluating interionic effects on internal quality of citrus in Sierra Leone.