scholarly journals Kinetics of potassium release in sweet potato cropped soils: a case study in the highlands of Papua New Guinea

Solid Earth ◽  
2015 ◽  
Vol 6 (1) ◽  
pp. 217-225 ◽  
Author(s):  
B. K. Rajashekhar Rao

Abstract. The present study attempts to employ potassium (K) release parameters to identify soil-quality degradation due to changed land use patterns in sweet potato (Ipomoea batatas (L.) Lam) farms of the highlands of Papua New Guinea. Rapid population increase in the region increased pressure on the land to intensify subsistence production mainly by reducing fallow periods. Such continuous cropping practice coupled with lack of K fertilization practices could lead to a rapid loss of soil fertility and soil-resource degradation. The study aims to evaluate the effects of crop intensification on the K-release pattern and identify soil groups vulnerable to K depletion. Soils with widely differing exchangeable and non-exchangeable K contents were sequentially extracted for periods between 1 and 569 h in 0.01 M CaCl2, and K-release data were fitted to four mathematical models: first order, power, parabolic diffusion and Elovich equations. Results showed two distinct parts in the K-release curves, and 58–80% of total K was released to solution phase within 76 h (first five extractions) with 20–42% K released in the later parts (after 76 h). Soils from older farms that were subjected to intensive and prolonged land use showed significantly (P < 0.05) lower cumulative K-release potential than the farms recently brought to cultivation (new farms). Among the four equations, first-order and power equations best described the K-release pattern; the constant b, an index of K-release rates, ranged from 0.005 to 0.008 mg kg−1 h−1 in the first-order model and was between 0.14 and 0.83 mg kg−1 h−1 in the power model for the soils. In the non-volcanic soils, model constant b values were significantly (P < 0.05) higher than the volcanic soils, thus indicating the vulnerability of volcanic soils to K deficiency. The volcanic soils cropped for several crop cycles need immediate management interventions either through improved fallow management or through mineral fertilizers plus animal manures to sustain productivity.

2014 ◽  
Vol 6 (2) ◽  
pp. 2843-2865 ◽  
Author(s):  
B. K. Rajashekhar Rao

Abstract. The present study attempts to employ K release parameters to identify soil quality degradation due to changed land use pattern in sweetpotato (Ipomoea batatas (L.) Lam) gardens of Highlands of Papua New Guinea. Soils with widely differing exchangeable and non-exchangeable K contents were successively extracted 569 h in 0.01 M CaCl2 and K release data was fitted to four mathematical models: first order, power, parabolic diffusion and Elovich equations. Results showed two distinct parts in the K release curves and 58–80% of total K were released to solution phase within 76 h (first 5 extractions) with 20–42% K released in the later parts (after 76 h). Soils from older gardens which were subjected to intensive and prolonged land use showed significantly (P < 0.05) lower cumulative K release potential than the gardens which are recently brought to cultivation (new gardens). Among four equations, first order and power equations best described the K release pattern and the constant b, an index of K+ release rates, ranged from 0.005–0.008 mg kg−1h−1 in first order model, and was between 0.14 and 0.83 mg kg−1h−1 in power model for the soils. In the non-volcanic soils, model constant b values were significantly (P < 0.05) higher than the volcanic soils thus indicative of vulnerability of volcanic soils to K deficiency. The food garden soils need management interventions either through improved fallow management or through mineral fertilizers plus animal manures to sustain productivity.


2003 ◽  
Vol 32 (3) ◽  
pp. 173-182 ◽  
Author(s):  
Alfred E. Hartemink

This paper summarizes a series of field experiments that investigated the effects of organic and inorganic nutrients on sweet potato tuber yield in the humid lowlands of Papua New Guinea. In the first experiment, plots were planted with Piper aduncum, Gliricidia sepium and Imperata cylindrica, which were slashed after one year, whereafter sweet potato was planted. Sweet potato yield was lowest after Gliricidia fallow, but no yield differences were found after piper and imperata fallow. In the second season, there was no significant difference in sweet potato yields. The second experiment consisted of a factorial fertilizer trial with four levels of N (0, 50, 100, 150 kg ha–1) and two levels of K (0, 50 kg ha–1). Nitrogen fertilizers increased yield in the first season, but depressed tuber yields in the second and third seasons. Potassium fertilizer had no effect on marketable tuber yield. The third experiment consisted of a comparison between N from inorganic fertilizer and poultry litter at four rates (0, 50, 100, 150 kg ha–1). No difference was found between the inorganic fertilizer and poultry litter, and the highest yields were found at 100 kg N ha–1. In the second season no significant response was observed. Although yield variation was considerable, this series of experiments has shown that sweet potato yield can be significantly increased by inorganic or organic N applications. Sweet potato yields after fallows were less variable than after inorganic nutrient inputs. Inputs of inorganic fertilizer or poultry litter may strongly increase or decrease tuber yields.


2019 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Hendri

Indonesia is one of the countries with the largest tropical rainforest area, especially in Papua Island together with Papua New Guinea accounted the third largest tropical rainforests in the world, after the Amazon (336.7 million ha) and Congo (181.3 million ha). The total tropical rainforest area is 68.7 million ha contained Papua about 57% (39.2 million ha) and 43% (29.5 million ha) Papua New Guinea. Unfortunately, deforestation rates in the few decades increased from 1.39 million ha in the period 1985 – 1997 and 0.6 million ha in the period 2000 – 2005. The direct impact of rapid LULUCF (Land Use, Land Use Change & Forestry) changes since 1980`s has accumulated critical land by 29.0% of forest area in West Papua and 31.4% of forest area in Papua. Climate change affected in Papua region due to rapid amount GHG`s emissions into the atmosphere by increasing average temperature about 0.7oC, minimum temperature (0.7oC) and maximum temperature (1.2oC) during period 1996 – 2005. Other effects of climate change the decreased rainfall up to 26% per month in the last decade, 50% reduced total agriculture productivity, expanded malaria diseases, and increased extreme condition such as drought with intensity of forest fire detected in Sorong due to inter-annual climate variability events, such as the El-Niño event and flood due to the La-Niña event. However, it is difficult task to build mitigation and adaptation planning in the region or local scale due to the lack information, the lack human resources, and local topography and phenomena. In that case, so far, no study has been conducted in Papua region to build mitigation and adaptation planning for carbon management. Therefore, this study tries to promote a carbon management program for help local government to solve forest environmental problems consideration of climate change.


2021 ◽  
pp. 1-25
Author(s):  
Kirt Hainzer ◽  
Catherine O’Mullan ◽  
Chris Bugajim ◽  
Philip Hugh Brown

Author(s):  
J. C. David

Abstract A description is provided for Alternaria bataticola. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOST: Ipomoea batatas. DISEASE: Leaf spot of Sweet Potato. GEOGRAPHICAL DISTRIBUTION: Africa: Central Africa, Burundi. Asia: Japan, Papua New Guinea. TRANSMISSION: By wind dispersal of airborne conidia.


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