An evaluation of nutritional constraints on sweet potato (Ipomoea batatas) production in the central highlands of Papua New Guinea

Abstract

Sweet potato (Ipomoea batatas) is the staple food crop in the highlands of Papua New Guinea (PNG). Declining crop productivity, however, appears to be threatening the sustainability of sweet potato-based farming systems within the region, a probable cause being the exhaustion of soil nutrient reserves in continuously cultivated sweet potato gardens. To assess the extent of the problem, a survey of sweet potato gardens was conducted across four of the highlands provinces and information on soil and crop variables was obtained for old gardens (cultivated over many seasons) and new gardens (newly brought into cultivation) on soils of volcanic and non-volcanic origin. Crop leaf nutrient data collected in the survey were interpreted using the Diagnosis and Recommendation Integrated System (DRIS), to try to identify the main nutritional constraints on tuber production in different garden types on soils of volcanic or nonvolcanic origin. The results suggested that K deficiency was the primary cause of poor crop production in almost a third of sweet potato gardens, but was more of a problem in old gardens than in new. Phosphorus deficiency was also a problem on volcanic soils, and S deficiency on non-volcanic soils. These latter deficiencies, however, were at least as prevalent in new gardens as in old. Important factors contributing to K and S depletion from garden systems were the removal of K and S-rich vines from cultivation areas, the shortening of fallow periods and the burning of weed and crop residues, the latter releasing S (SO 2 ) to the atmosphere.

Invertebrate pests and diseases of sweetpotato (Ipomoea batatas): a review and identification of research priorities for smallholder production

“…Further, smallholders often grow successive sweetpotato crops on a given area of land, leading to considerable yield differences compared with sweetpotato crops grown immediately after a fallow period. Differences result partly from soil and plant nutrition factors (Bailey et al, 2009;Hughes et al, 2009) but also from the build-up of pests and pathogens. Human population growth in less developed countries is also leading to an increase in cropping intensity with shorter fallow periods and more years of continuous cropping (Bourke, 2001).…”

“…This has the dual effect of further depleting soil nutrient levels and increasing the potential for pest and pathogen build-up . Associated with this, the adoption of strategies to manage nutrition, such as not burning crop residues (Bailey et al, 2009), can affect the carryover of pests and pathogen inocula. The build-up of pests and pathogens is exacerbated by the fact that sweetpotato is propagated vegetatively.…”

Response surface methodology for optimisation of soluble dietary fibre extraction from sweet potato residue modified by steam explosion

“…A small proportion of SPR is used as animal feed, but SPR has not yet been used on a mass-scale, because after microbial decomposition, it can easily pollute the environment. Bailey et al(2008) have found that SPR is a good source of dietary fibre (DF), containing more than 50% and can be categorised into soluble dietary fibre (SDF) or insoluble dietary fibre (IDF) (Zhang & Wang, 2013). Studies have shown that DF plays an important role in maintaining human health by preventing diseases such as coronary heart disease, colon cancer, obesity and diabetes (Esposito et al, 2005;Yang et al, 2006), with SDF appearing to be more effective than IDF (Zhang et al, 2011).…”

Morphological, crystalline, thermal and physicochemical properties of cellulose nanocrystals obtained from sweet potato residue

“…The SPR is mainly composed of residual starch and cellulose fibers (Bailey, Ramakrishna, & Kirchhof, 2009). After removing the residual starch, the content of cellulose fibers is about 75 wt.%.…”