Cassava is generally grown by poor farmers living in marginal areas with adverse climatic and soil conditions. The crop is very suitable for these conditions because of its exceptional tolerance to drought and to acid, infertile soils. It is often grown on sloping land because of its minimal requirement for land preparation, and its ability to produce reasonably good yields on eroded and degraded soils, where other crops would fail. It has been shown (Quintiliano et al., 1961; Margolis and Campos Filho, 1981; Putthacharoen et al., 1998), however, that growing cassava on slopes can result in severe erosion, with high soil and nutrient losses. Thus cassava cultivation on slopes requires adequate cultural and soil conservation practices that minimize erosion (Howeler, 1994). Cassava is well adapted to poor or degraded soils because of its tolerance to low pH, high levels of exchangeable aluminium (Al) and low concentrations of phosphorus (P) in the soil solution. Studying the effect of pH on the growth of several crops grown in flowing nutrient solution, Islam et al. (1980) reported that cassava and ginger (Zingiber officinale) were more tolerant of low pH (< 4) than tomatoes (Lycopersicon esculentum), wheat (Triticum aestivum L.) or maize (Zea mays L.). Centro Internacional de Agricultura Tropical (CIAT; 1978) and Howeler (1991a) also reported that cassava and cowpeas (Vigna unguiculata) were more tolerant of acid soils with high levels of exchangeable Al, and were much less responsive to lime applications than common beans (Phaseolus vulgaris), rice (Oryza sativa), maize and sorghum (Sorghum vulgaris).

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Cassava mineral nutrition and fertilization

Publisher Summary This chapter reviews three main aspects of K+ in crop production—namely, K availability in the soil, the function of K+ in the plant, and potash fertilizer application. The soil is considered as a source of K+ to plant roots. The use of K+ in practical crop production is also emphasized in the discussions on the physiological role of K+ in the plant and in fertilizer application. The potassium status of a soil may be assessed on its content of K+-bearing minerals because the amount of these minerals present in a soil gives some indication of the potential source of K+ to plants. However, in terms of the ability of the soil to supply K+ to plant roots, the quantity of K+-bearing minerals plays only an indirect role. More important in determining the K+ supply to plants are the soil K+ fractions. These fractions, which have been established experimentally using different extraction techniques, are soil solution K+, K+ adsorbed to clay minerals or humus, and K+ present in minerals.

Potassium in crop production.

Cassava improvement in Africa

Tillage and fertilizer influenced soil characteristics through their effects on soil properties which in turn affect crop performance. Field experiments were conducted during 2006 and 2007 cropping seasons on an Alfisol (Oxic Tropuldalf) at Owo in the forest-savanna transition zone of Nigeria to evaluate the effect of tillage and fertilizer types on soil properties and sweet potato yield ( Ipomoea batatas L.). Two tillage treatments namely: zero tillage (ZT) and conventional tillage (CT) were combined with each of NPK-15-15-15 fertilizer at 250 kg ha −1 , poultry manure (PM) at 10 t ha −1 , combined application of 125 kg ha −1 NPK 15-15-15 fertilizer + 5 t ha −1 poultry manure and a control (no fertilizer/manure). The experiment was laid out on a randomized complete block design in a factorial combination of eight treatments that were replicated three times. The surface soil (0–15 cm depth) was chemically analysed before and after crop harvest and some selected soil physical properties, leaf nutrient concentrations, growth and sweet potato yield were determined. Conventional tillage plots had significantly lower soil bulk density (1.30 Mg m −3 ) than zero tillage plots and resulted in higher leaf N, P, K, Ca and Mg and tuber yield of sweet potato compared with zero tillage. Soil water content was higher, whereas temperature was lower, in zero tillage than conventional tillage. Zero tillage had significantly higher concentrations of soil pH, organic C, N, P, K, Ca and Mg for surface soil (0–15 cm depth). Conventional tillage increased mean tuber yield of sweet potato by 30% compared with planting on untilled zero soil. Application of poultry manure alone and complementary application of NPK fertilizer and poultry manure reduced bulk density and temperature and increased soil water content and porosity, whereas NPK fertilizer did not improve soil physical properties. Compared with control, poultry manure alone, NPK fertilizer alone and complementary application of NPK fertilizer and poultry manure increased soil total N, available P, and exchangeable K, Ca and Mg concentrations as well as leaf N, P, K, Ca and Mg concentrations. Poultry manure tended to improve soil pH, SOC, N, Ca and Mg compared with NPK fertilizer. Combined application of sub-optimal rates of NPK fertilizer and poultry manure gave higher soil and leaf N, P and K concentrations, vine length, vine girth, leaf area and tuber yield compared with NPK fertilizer or poultry manure alone. Compared with control, NPK fertilizer, poultry manure and NPK fertilizer plus poultry manure increased tuber yield by 39, 45 and 83%, respectively. Conventional tillage in combination with NPK fertilizer plus poultry manure gave the highest tuber yield of sweet potato.

Tillage and fertilizer effects on some soil properties, leaf nutrient concentrations, growth and sweet potato yield on an Alfisol in southwestern Nigeria

Historical contingencies in the coevolution of environment and livelihood: contributions to the debate on Amazonian Black Earth

The results of field experiments on the influence of nitrogen fertilization on the yield components, starch and prussic acid content of two of the cassava cultivars recommended for cultivation in Nigeria are presented. The two cultivars 53101 (local) and 60506 (improved) were harvested at 9, 12 and 15 months. In general, the improved cultivars appeared to respond better to N fertilization, but high rates of N (150 kg N/ha) tended to reduce the yield performance of the two cultivars. The local cultivar produced maximum yields of 31·5, 37·5 and 55·7 fresh tuber t/ha with 60 kg N/ha at 9, 12 and 15 months, respectively, while the improved cultivar gave maximum yields of 31·5 and 48·4 t/ha with 120 kg N/ha at 9 and 12 months, respectively, and 64·1 t/ha with 90 kg N/ha at 15 months. By allowing the crop to grow up to 15 months, the starch yield was more than doubled and about three times the yield obtained at 9 months. The 53101 strain seemed to produce maximum starch yields with 60 kg N/ha while the 60506 type tended to give maximum starch yields with 90 kg N/ha. Influence of N treatments was significant up to 12 months of age but not at 15 months.The HCN content of both cultivars diminished considerably with the age of the plant, dropping at 15 months to about half the level at 9 months. While the HCN concentration of the local cultivar tended to increase with higher N-fertilization, that of the improved cultivar diminished, particularly at 12 months after planting. At 15 months however, the HCN content of both cultivars rose with increasing N. fertilization.

Investigations on Nigerian root and tuber crops. Influence of nitrogen fertilization on the yield and chemical composition of two cassava cultivars ( Manihot esculenta )

The response of three cassava cultivars to potassium fertilizer was studied in field experiments during 1972–3, 1973–4 and 1975–6. They included the local cultivar 53101 and the improved cultivars 60506 and 60447 which were F1 hybrids involving the local strain (53101) and cultivar 42074. In locations known to be low in potassium, the cassava cultivars showed only low response to K fertilizer with optimum performance at about 60 kg K2O/ha, but the local cultivar 53101 had apparently not reached its maximum tuber production even at 120 kg K2O/ha. This cultivar gave higher tuber yield increases (10–18 kg dried tuber) per unit weight of potash than the 60506 cultivar (6–10 kg dried tuber/kg K2O) while cultivar 60447 produced about 18 kg/kg K2O. Unfertilized 60506 produced average yields equivalent to those obtained from the heavily fertilized 53101 cultivar. Cultivar 60506 gave the highest dry-matter content. The improved cultivars retained more leaves than the local strain. K fertilizer enhanced the utilization index (storage root/top ratio) of the cassava cultivars.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0021859600027155

Investigations on Nigerian root and tuber crops: response of cassava cultivars to potassium fertilizer in Western Nigeria

Summary Field experiments were made in the rainforest zone of Western Nigeria over three cropping seasons on the effects of potassium fertilizer of one local cassava cultivar 53101 and two improved cultivars 60506 and 60447 which were F1 hybrids of the former. The results showed that K-fertilizer increased the starch yields only slightly. Cultivar 60506 produced significantly higher starch yields (P < 0–01) than the local strain, 53101, while cultivar 60447 gave lower starch recovery than the local cultivar. A definite influence of K application on the cyanide (HCN) content of the tuber roots could not be established. The peeled tubers of the improved cultivars contained much less cyanide than those of the local 53101 strain (P < 0–01). Potassium had the highest (0·72–1·28% dry weight basis) while phosphorus had the lowest concentration (0·06–0·12%) in the peeled tuber. Owing to its higher yielding capability the unfertilized 60506 removed larger amounts of potash (average 110·9 kg k20/ha) from the soil than unfertilized 53101 (average 82·2 kg k20/ha).

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0021859600027167

Investigations on Nigerian root and tuber crops: effect of potassium on starch yields, HCN content and nutrient uptake of cassava cultivars ( Manihot esculenta )

SUMMARY Experiments were carried out over two growing seasons to find out the effects of fertilizer application and age at harvest on the yield, available carbohydrates and hydrocyanic acid content of Manihot palmata.Fertilizers were applied at the following rates: 0–0–0; 45–45–0; 45–45–45; 45–45–67, and 45–45–90 kg/ha of nitrogen, phosphorus and potassium respectively. Harvests were at 9 and 15 months after planting. Application of nitrogen and phosphorus resulted in significant yield increases. Fertilizer application had no significant effect on the hydrocyanic acid content of the tubers. Harvesting at 15 months gave more than double the tuber yields and a higher percentage of hydrocyanic acid than harvesting at 9 months. It is, therefore, desirable to use efficient methods of processing the tubers harvested at 15 months to obtain safe products for industrial and nutritional uses.

Effects of Age at Harvest and Fertilizer Application on the Yield, Available Carbohydrates and Hydrocyanic Acid Content of Cassava ( Manihot palmata Pohl)

G. O. Obigbesan

Papers

Investigations on Nigerian root and tuber crops. Influence of nitrogen fertilization on the yield and chemical composition of two cassava cultivars ( Manihot esculenta )

Investigations on Nigerian root and tuber crops: response of cassava cultivars to potassium fertilizer in Western Nigeria

Investigations on Nigerian root and tuber crops: effect of potassium on starch yields, HCN content and nutrient uptake of cassava cultivars ( Manihot esculenta )

Effects of Age at Harvest and Fertilizer Application on the Yield, Available Carbohydrates and Hydrocyanic Acid Content of Cassava ( Manihot palmata Pohl)