Phosphorus requirements of some selected soil types in the Fiji sugarcane belt

Abstract

The availability of phosphorus (P) in soil is perceived to be one of the limiting factors to sustainable sugarcane production in Fiji. The main objective of this research was to ascertain the amount of bioavailable phosphorus in some Fiji sugarcane growing area soils; this will be valuable in improving the determination of the required amount of inorganic fertilizer to be applied to the soil. In this study, twelve different soils were selected from the sugarcane belt of Fiji and phosphorus buffer index (PBI) and phosphorus isotherm experiments were performed. Soil physical and chemical parameters were also measured and Pearson's correlation tests used to identify patterns. It was found that Oxisols had the highest PBI values ranging from 134 to 170 while Inceptisols had the lowest ranging from 33 to 54. The PBI data followed a similar pattern to the generated isotherm curves of the different soil types. Most interest was in identifying soils with low PBIs as they have greater potential for P leaching through runoff into waterways. Clay content showed a strong positive correlation with PBI (R = 0.76, p ≤ 0.005). There is strong association with phosphorus fixation in soil with increasing levels of Al and Fe in the soil. Phosphorus availability and P fixation varied with soil types.

Assessment of Phosphorous Release from Bat Guano with Respect to Their use as Organic Fertilizers in Crop Production

“…These results are in line with observations made by [46]. The results also agreed with findings attained by [47]. [47] reported that phosphorus availability is higher in moderately acidic soil.…”

“…The results also agreed with findings attained by [47]. [47] reported that phosphorus availability is higher in moderately acidic soil. Moreover, in this study, the pH decreased as the rate of guano increases probably because of acidic nature of the guano.…”

Impacts of Tropical Rainforest Conversion on Soil Nutrient Pools in Viti Levu, Fiji

“…Relatively low pH values may also be attributed to the acidic nature of the parent material (Garrison-Johnston et al 2007, Oshunsanya 2019, Zhang et al 2019. Low soil pH has been reported by several other workers in Fiji (Curtin et al 1991, Waterloo 1994, Goundar et al 2014, Morrison 2019, Nisha and Prasad 2020, Vessel and Simonson (1958) in Palau and Reverchon (2015) in Solomon Islands. Soil pH was highest in plantation followed by primary forest while secondary forest had the lowest soil pH.…”

“…The mean Olsen available phosphorous was 0.87 mg/kg; classified very low as per Blakemore et al (1987). Low phosphorous levels have also been detected by Curtin et al (1991), Naidu et al (1991), Goundar et al (2014) and Nisha and Prasad (2020) in soils of Fiji. The paradigm of phosphorous limitation (Dalling et al 2016) suggests that phosphorus is the most important limiting nutrient in lowland tropical rainforests with the largest pool of plant available phosphorous actually present in biomass (Turner and Engelbrecht 2011, Yang et al 2016, Nasto et al 2017.…”