Open Access Original Research Article

The Impact of Phosphorous Applications and Incubation Periods on P- Desorption Characteristics with Successive DMT-HFO-P Extractions on P Fixing Soils

V. A. Ochwoh, E. Nankya, P. C. De Jager, A. S. Claassens

International Journal of Plant & Soil Science, Page 1-14
DOI: 10.9734/IJPSS/2016/27884

Aim: The overall objective of this study was to establish the rates and how much of the transformed or fixed Phosphorus can be available to plants over time, having determined the extent of Phosphorus fixation by both Rustenburg and Loskop soils.

Methodology: Therefore, the impact of applied Phosphorus rates (0, 25, 50, 100, and 200 mg kg-1) and incubation period (1, 120, and 240 days) on the Phosphorus desorption rates of a red-sandy clay soil (high P fixing) and a red-sandy loam soil (low P fixing), were investigated. Cumulative and sequential P extractions/desorption were carried out for 1, 7, 14, 28, and 56 days per treatment combination to determine Phosphorus (P) transformations.

Results: About 30 – 60% of Phosphorus added was transformed into less stable P pools within one day and 80-90% after 120 days. The transformation of P applied to less labile P pools was faster in the red-sandy clay soil (high P fixing) than in the red-sandy loam soil (low P fixing). The cumulative DMT-HFO-P extraction curves of the Rustenburg and Loskop had not reached plateaux, indicating that desorption rate could proceed for a much longer period than the 56 days. This is important for crops such as tobacco due to residual effects of the added Phosphorus fertilizer and thus lower application rates.

Conclusion: Much as Rustenburg soil is reflected to be a high P fixing, the P release rates are still more able to meet most of crops requirements; however, importantly is may depend on how much of the soil volume is exploited by the root system of a particular crop.

Open Access Original Research Article

Effect of Urine Sources on Some Soil Health Indicators, Maize Yield and Its Heavy Metals Uptake in Abakaliki, Southeastern Nigeria

J. N. Nwite

International Journal of Plant & Soil Science, Page 1-8
DOI: 10.9734/IJPSS/2016/29016

The need to find alternative to inorganic fertilizer which is costly and not easily affordable to local farmers necessitates research in rare areas. Thus, this experiment was carried out at the Plant and Screen house to study effect of urine sources on some soil health indicators, maize yield and its heavy metals uptake. Completely Randomized Design was used in laying the experiment. 20 kg of sieved soil was treated with different urine sources replicated five times. The result indicates that soil pH, total N and organic matter were significantly (P<0.05) higher in different urine sources than control. Human urine had significantly (P<0.05) higher treatment effect on soil pH, percent total N and organic matter compared to other sources of urine. Similarly, human urine was 9-10%, 15-27%, and 10-47% higher in number of leaves, plant height, and grain yield of maize when compared to those of cattle and goat urine sources. Significantly (P<0.05) higher copper and lead uptake by maize grains were obtained in control relative to those of urine sources. Copper and lead uptake by maize grains were respectively higher by 20, 80, 87% and 87, 47, 7% in control when compared to human, cattle and goat urine sources. Generally, heavy metals uptake by maize grains is below recommended safe limits for toxicity. Urine from adult animals is recommended as credible alternative for improvement of soil health status and sustainable productivity.


Open Access Original Research Article

Effects of Rhizobia Inoculation, Phosphorus and Potassium on Chlorophyll Concentration of Soybean Grown under Maize Intercropping System

Daniel Nyoki, Patrick A. Ndakidemi

International Journal of Plant & Soil Science, Page 1-10
DOI: 10.9734/IJPSS/2016/30710

Aims: The study was conducted to assess the effects of Rhizobia inoculation, supplemented with phosphorus (P) and potassium (K) under intercropping system on soybean chlorophyll content.

Study Design: The design of the experiment was split-split plot with three factors factorial and replicated thrice.

Place and Duration of Study: The experiment was carried out for two consecutive years 2015 and 2016 at the Tanzania Coffee Research Institute farm in Northern Tanzania.

Methodology: Two inoculation treatments, four intercropping systems and seven fertilizer levels (kg ha-1): Control, 20, 40 K, 26, 52 P, 26 P + 20 K and 52 P + 40 K. Chlorophyll concentrations were extracted using dimethyl sulphoxide (DMSO). Spectrophotometer was used to read the absorbance values at 645 nm (Chlorophyll b) and 663 nm (Chlorophyll a).

Results: Rhizobia inoculation significantly (p=.05) increased total soybean leaf chlorophyll content from 4.25±0.30 to 5.32±0.34 and 7.20±0.27 to 7.88±0.29 in 2015 and 2016 cropping seasons respectively. P and K fertilization also significantly (p=.05) increased soybean total leaf chlorophyll content from 1.69±0.23 to 7.17±0.51 and 4.62±0.33 to 9.87±0.48 in 2015 and 2016 cropping seasons respectively. The combined fertilizers had higher mean values of chlorophyll concentration over all other treatments in both 2015 and 2016 cropping seasons.

Conclusion: Therefore, for improved chlorophyll concentration, P and K should be applied in combination at low rate of 20 K + 26 P (kg ha-1). Doubling of these fertilizers may be costly and will not significantly change the leaf chlorophyll content.

Open Access Original Research Article

Mitigation of the Effect of Crude Oil Polluted Soil on the Growth and Development of Cassava-Manihot esculenta Crantz with Organic and Inorganic Amendments

P. O. Eremrena, L. A. Akonye

International Journal of Plant & Soil Science, Page 1-11
DOI: 10.9734/IJPSS/2016/27058

NPK and compost of Centrosema pubescens were studied at the University of Port Harcourt Botanic garden for their effect on the growth components of Manihot esculenta, Crantz (NR 8082) in a crude oil polluted soil. The soil samples were polluted at four different levels (0%, 2%, 4% and 6%) with crude oil and amended with organic supplement (decomposed Centrosema pubescens) and NPK fertilizer at the rate of 0.25 Kg per 5 Kg of soil to the various levels of crude oil contaminated soil, alongside a control. A total of 48 plastic buckets were used, each treatment was replicated three times.

Mean values of Physico- chemical properties of experimental soils were expressed. Quantitative observations showed that amelioration treatments recorded significant (P=0.05) increase in plant height, petiole length, leaf number, leaf area, fresh weight, dry weight and moisture content, than those of the control. Results of edaphic physico-chemical parameters showed that crude oil pollution at P=0.05 significantly increased percentage total organic carbon, total organic matter and total hydrocarbon content (THC) while pH, percentage total nitrogen, phosphorus and cation nutrients (Ca, K and Mg) were significantly decreased at two weeks after pollution. The results also showed that the amendment treatments at P=0.05 significantly decreased crude oil toxicity at different degrees by improving the nutrients content and decreasing the total hydrocarbon content of the soil.

Therefore, Centrosema pubescens and NPK fertilizer in single and combined treatments is effective in remediation of crude oil polluted soil for cassava cultivation.

Open Access Original Research Article

Soil Quality Assessment for Sustainable Land Use and Management

O. D. Adeyolanu, A. O. Ogunkunle

International Journal of Plant & Soil Science, Page 1-11
DOI: 10.9734/IJPSS/2016/22136

Tropical soils are generally fragile and hence highly degraded due to such factors as low organic matter content, dominance of low activity clay, high susceptibility to erosion etc. Coupled with this, there is population pressure on the limited land and this has become a great challenge for land management and agricultural production. It is therefore imperative to adopt science-based and efficient approach for monitoring the impact of land use on land resources. This study has assessed soil quality under two land use types to establish the effect of land use on soil quality and demonstrate the kind of assessment necessary to arrest land degradation before it progresses too far. It was conducted within Oluyole Local Government Area in Oyo State, Southwestern Nigeria under two agricultural land use types (cacao and maize). For each of the two land uses, two farmlands were chosen for the study. In each of the farmlands, five sampling points were located and soil samples were collected at 0 – 15 cm and 15 – 30 cm depths. The samples were processed and analyzed for selected indicators, following standard methods. Soil quality was assessed using Soil Management Assessment Framework. Sustainability assessment was carried out on a scale of < 20 (highly sustainable) to > 40 (not sustainable) - i.e. ‘less is better’. The relationship between soil quality and sustainability was established using regression analysis. Soil quality index was 85 – 87% under cacao and 60 – 77% under maize. Sustainability index ranged from 14 – 19 (highly sustainable) under cacao to 25 – 28 (moderately sustainable) under maize. High positive linear relationship (R= 0.86 and 0.94) was obtained between soil quality and sustainability. The results thus indicate that the land use and management systems in the farms studied are sustainable, although the arable land use requires closer monitoring.


Open Access Original Research Article

Forms and Levels of Phosphorus in a Strongly Weathered Acid Soil in Ghana: The Contribution of Corn Cob Biochar

B. A. Osei

International Journal of Plant & Soil Science, Page 1-7
DOI: 10.9734/IJPSS/2016/30888

Different rates of corn cob biochar were applied to a strongly weathered acid soil as an amendment. The impact of the amendment on levels and forms of phosphorus (P) was determined. The biochar was applied to the soil at a rate of 0, 26, 52, 78 and 150 t ha-1. The amended soil was incubated in a greenhouse for a period of 1 – 8 weeks. Sub samples of the unamended/control and amended soils were taken at periods of 2, 4, 6 and 8 weeks and then analysed for pH, total P, Bray – 1 P and water – extractable P. Significant improvements were recorded in the pH of the amended soil. The application rate of 150 t ha-1 recorded the highest increase in pH (78.4%) while the lowest change (64.9%) was recorded by the application rate 52 t ha-1. The total P decreased as the rate of amendment increased, implying that total P was mineralized as the amount of carbon in the amendment increased. This resulted in the increase in available P. The yield of lettuce (Lactuca sativa) generally increased with rate of biochar application but the P content in the shoot of the plant was less than the optimum.