Comparison Of Six Extractants For Assessing Available Phosphorus, Zinc And Manganese In Selected Nigerian Soils

Interactions between soil available phosphorus (P) and micronutrients [particularly zinc (Zn) and manganese (Mn)] are becoming increasingly significant for sustainable crop production in many countries of the world (including Nigeria) with highly weathered acid or calcareous alkaline soils. The nutrient extraction methods in use consume time and many other resources. In this work, the relative suitability of six extractants [Deionised-H2O, 1N NH4OAc, 0.1M HCl, 0.01M CaCl2, Bray-1 and electro-ultra-filtration (EUF) technique] for simultaneous assessment of the availability of these nutrients in selected Nigerian soils was evaluated using guinea-corn (Sorghum bicolor) as test crop in Neubauer experiment. The respective average amounts of P, Zn and Mn extracted by 1N NH4OAc (63.86, 12.6 and 50.12 mg/kg) are about six-, three- and five times more than those of deionised-H2O (10.09, 4.06 and 5.03mg/kg) which constituted only 0.49, 0.18 and 0.10% of total P, Zn and Mn, respectively in the soils. Phosphorus was the least extracted element, highest mean value being 22.66mg/kg (Bray-1) compared with 155.31mg Mn/kg and 33.56mg Zn/kg. The EUF technique extracted the greatest amount of Zn, followed by 0.1M HCl, 1N NH4OAc, Bray-1, deionised-water and 0.01M CaCl2. One-tenth N HCl extracted about 70%, 76.5%, 81.5%, 87.6% and 100% more Mn than 1N NH4OAc, Bray-1, 0.01M CaCl2, EUF technique and deionised-water, respectively. The water-soluble (deionised-H2O extractable) and exchangeable (1N NH4OAc – extractable) nutrient forms were poorly correlated with plant parameters whereas the relationship between the plant parameters and P or Mn extracted by the different methods showed that the EUF technique could be used to assess P and Mn availability in the soils. One percent M CaCl2 was observed to be best for assessing Zn availability to the sorghum plants. It was quite obvious that none of the extraction procedures tested could be successfully employed as a multipurpose extractant for available-P, Zn and Mn. KEY WORDS: Multipurpose extractants, Electro-ultrafiltration technique, Phosphorus, Zinc, Manganese. Global Journal of Pure and Applied Sciences Vol.11(2) 2005: 179-18

Evaluation of potassium release and fixation behaviour of some Nigerian soils

In this study, K fixation and release parameters estimated for 25 Nigerian soils both by the conventional fixation methods and the electro-ultrafiltration (EUF) technique were related to some soil physico-chemical properties. This was to ascertain the suitability of the EUF to comprehensively characterize K dynamics in the experimental soils. Potassium fixation was higher and varied more under “wet”-condition (12.28-28.14 cmol kg-1) than under “wet-and-dry”-condition (5.63-14.33 cmol kg-1), representing 24.60-56.28% and 11.26-28.66% of fertilizer-K added. The fixation data obtained under “wet-and-dry”-condition, however, reflected K dynamics is the soils better than that of the “wet”-condition. Potassium desorption by EUF technique after 10 and 35 minutes, representing the intensity and quantity factors, ranged between 0.1 – 0.28 and 0.08 – 0.91 cmol kg-1, respectively with mean values of 0.08 and 0.20 cmol kg-1. The superiority of the EUF technique to provide the needed information on soil K dynamics better than the methods normally employed in fixation studies was demonstrated in this study. Nigerian Journal of Soil Science Vol. 15 2005: 47-5

Extractable Micronutrients In Relation To Physico-Chemical Properties Of Soils In Four Ecological Zones Of Nigeria

Micronutrients play an important role in crop production. Discerning their bioavailability is a necessity to diagnose deficient or toxic levels. Yet, the non-static nature of the complex reservoir of mineral nutrients (the soil) is implied in biological, physical and chemical changes that also affect the supply of micronutrients to crops. In this study, total and 0.01N HCl extractable Mn, Zn, Fe and Cu were determined in 25 soil samples collected from various locations representing the major soil types and parent materials found in the Rainforest, Derived savannah, Coastal rainforest and Northern guinea savannah ecological zones in Nigeria. The resulting analytical values were subsequently related to the physico-chemical properties of the soils. There were substantial variations in the amounts of total and extractable micronutrients. Total Mn and Zn ranged from 24.00 to 114.00 and 14.00-54.00 mg kg-1 with means of 60.55 and 23.55mg kg-1, respectively while the 0.1N HCl-extractable Mn, Fe, Cu and Zn values varied from 0.03-14.21, 10.00-100.00, 0.27-0.46 and 0.60-95.50 mg kg-1, the means being 4.82, 62.32, 0.35 and 6.91mg kg-1, respectively. Majority of the soils are not deficient in Mn and Zn while none was deficient in Fe and Cu. Extractable Mn correlated significantly with organic carbon (OC) (r=-0.413) while total Zn correlated with soil pH (-505) and OC (+0.521). Organic matter and the clay fractions had strong influence on the contents of Mn. Soil reaction (pH) and could be used to predict Zn contents whereas there was no assurance that 0.1NHCl-extractable Fe and Cu values could be predicted from the physico-chemical properties. In view of their relatively low correlation coefficients with soil properties, it appears that the 0.1N HCl test procedure proved to be a non- promising extractant for the determination of available micronutrients in the soils tested. KEY WORDS: 0.01N HCl extractable, Bioavailability, Micronutrients, Physico-chemical properties, Relationship. Global Journal of Pure and Applied Sciences Vol.11(2) 2005: 197-20

Comparative performance fo soybean (glycine max) in response to groound phosphate rock and superphosphate fertilizer treatments in two tropical soils in Nigeria

No Abstract. Global Journal of Agricultural Sciences Vol. 6 (1) 2007: pp.81-8

Efficiency of indigenous ground phosphate rocks, organic fertilizer and their mixtures for maize performance in two Nigerian alfisols

Greenhouse experiments were conducted to evaluate main and residual effects of sole and combined applications of ground rock phosphates (GRP) and organic fertilizer, (OF) on maize performance in two Nigerian alfisols. A commercial OF (1.33% P2O5), Ogun RP (31.00% P2O5), Sokoto RP (36.10% P5O2) and mixtures of OF with either ORP or SRP were used as “test” fertilizers while single super phosphate (SSP) was the “standard” P fertilizer. There were 7 fertilizer sources (OF, ORP, SRP, SSP, OF+ORP, OF+SRP and OF+SSP), each applied at 2 levels (25 and 50mg P2O5kg-1). The 14 treatments and the control were replicated 3 times in each of 2 soil types (a medium acid Oxic paleustalf, A, from Zaria and another low acid Typic paleustalf, B, from Ibadan), to give a total of 90 experimental pots arranged in completely randomised design (CRD). In the first cropping, the weakly acid soil, B produced taller maize plants (62.3cm) than the medium acid soil, A (60.3cm) after six weeks of growth. However, plants treated to 50mg P2O5 kg-1 of OM+SRP were the tallest (66.3 cm) while the untreated ones were the shortest (55.1cm). In the second cropping, differences in height between plants given the various fertilizer treatments were recorded as early as the 3rd week of growth but there was no difference due to soil type even after five weeks. There was no difference in forage yield that could be attributed to the various fertilizer treatments in the first cropping. During the 2nd cropping, however, SRP, ORP and OF+ORP (at 25mg P2O5 kg-1) as well as OF (at 50mg P2O5 kg-1) treatments produced higher yields than the control. However, highest P uptake (about 23.5mg pot-1) was recorded by plants grown under the influence of OF and SSP fertilizer mixture, irrespective of the soil type. The lowest Relative Agronomic Efficiency (RAE) values estimated for the test fertilizer materials in the 1st cropping were 81.5 and 117.5% in soils A and B, respectively. The respective values for 2nd cropping were 78.3 and 62.0%. It was clear that the indigenous GRP, OF and their mixtures have great potentials as substitutes for the imported soluble P fertiliser sources in the medium and weakly acid alfisols. Key Words: Phosphate rocks; organic fertilizer; maize; Nigerian alfisols Moor J. Agric. Res. Vol.4(1) 2003: 1-

Response of cowpea varieties to phosphorus supply on an acidic Alumi-Haplic-Acrisol from Brazil

No Abstract. Nigerian Journal of Soil Science Vol. 16 (1) 2006: pp. 115-12