Variability of some soil properties along a toposequence in a basaltic parent material of Vom, Plateau State Nigeria

Topography influences the distribution of some soil physical and chemical properties. This study assessed some variation in soil properties resulting from the topographic effect on Basaltic parent material at Vom Jos Plateau State in the Southern Guinea zone of Nigeria. Soil samples were collected at an interval of 20m and at depths of 0 to15cm and 15 to 30cm, parceled, labeled and taken to the laboratory for analysis of the selected for analysis. The results from the study revealed that variations in soil properties along the landscape segments were probably due to their positions toposequence characteristics in soils. Clay, silt and gravel contents varied moderately (CV = 22.9, 15.42 and 32.55% respectively), while sand did not vary much (CV = 8.47%). Organic carbon showed high variability (CV = 38.08%) while soil pH in (H2O and CaCl2) showed less spatial variability (with CV = 4.91 and 6.45% respectively). Available phosphorus has high variability (CV = 37.59%). Magnesium, K and Ca showed high spatial variability (CV = 42.60, 35.85, and 35.84% respectively), while Na and exchange acidity were moderately variable (CV = 24.39 and 24.27% respectively). Generally, some of the soil chemical properties were varied with topographic positions.

Assessment of relevant and exchange acidity of cespitose-podsolic sandy loamy soil when the Hotynetsky field zeolite is used

The following paper considers influence extent of zeolite breed of the Hotynetsky field on indicators of relevant and exchange acidity of the cespitose-podsolic sandy loamy soil in the Nizhny Novgorod Region. A three-year experiment, representing microfield experiment, was started in 2014 in the Borsky District Elitkhoz. Zeolite was brought in the plough-layer once in high doses - 3, 6 and 12 t/hectare. During the research (2015-2017) on allotments the main crops of the region were grown up. The acidity of the soil was estimated on рН indicators, defined from water and salt extracts which were selected during the autumn period after cultural plants harvesting. As a result of the conducted researches positive action of all doses of the studied zeolite on indicators of the acid and main mode of the cespitose-podsolic soil was established. The essential effect was traced already at the minimum dose of material: 12,0% increase of рНwater indicator and 6,3% increase of рНsalt indicator on average during the research time. Application of 6 t/hectare of zeolite breed in the greatest measure promoted reduction of the relevant acidity of the soil by 20%, exchange acidity - for 13% and also for 60% - to increase in an ionic exchanging of the soil solution system with preservation of the action force during the research time.

Risk of acidification of the organic shrimp model at Tam Giang commune, Nam Can district, Ca Mau province

This paper assesses the risk of acidification of the organic shrimp model certified by Naturland at Tam Giang commune, Nam Can district, Camau province. Pond water and sediment was sampled in 8 ponds in March, July and November 2015, dike soil and mangrove soils were sampled in March 2015. Pond sediment and mangrove soils are highly reduced (Eh of top sediment and soils to 60 cm depth range respectively from -299 – -1mV and -321 – -52mV). Pond water ranges from neutral to slightly alkaline (pH of pond water 7.01-8.82) and sediment from slightly acidic to slightly alkaline (pH of fresh sediment 6.05-7.64, pHH2O 6.63-7.78, pHKCl 6.35-7.43). Mangrove soils show a large pH range with very low minimums (pHH2O 3.72, pHKCl 3.05), reconfirming the presence of pyrite mineral in the soil profile. Mangrove soils deposited on the dikes (partly oxidized) are very acidic (pHH2O 2.51±0.72, pHKCl 1.81-2.14, exchange acidity 11.56±2.69 meq/100g). At the start of the wet season, pH of pond water reduces sharply as a result of reception of acidic components from the oxidized pyritic material (FeS2) on the dikes. The exchange acidity in pond sediment and mangrove soils are negatively correlated with organic matter, indicating that the decomposition of organic matter under reduced conditions contributes to exchange acidity in pond environment. Risk of acidification of the organic shrimp model is high due to managerial activities (mostly channel digging and disposal of pyrite-containing mangrove soils on the dikes).

Lime requirement of acidic Queensland soils. I. Relationships between soil properties and pH buffer capacity

The pH buffer capacity of 40 acidic surface soils (pHw <6.5) was determined from soil-CaCO3- moist incubations. Buffer capacity values ranged from 02 to 5.4 g CaCO3 kg-1 soil unit-1 pH increase. Organic carbon, clay content, ECEC, 1M KCl extractable acidity and Al, and the change in CEC with pH (�CEC) were measured and correlated with pH buffer capacity. Step-up multiple linear regression indicated that the effect of �CEC on buffer capacity was highly significant (r2 = 0.77, P <0.001), whereas that of exchangeable Al or exchange acidity was not. This suggests that deprotonation reactions, compared with exchangeable Al or exchange acidity, are considerably more important in determining buffer capacity. The major soil property affecting �CEC in our soils was the organic carbon content and, when step-up multiple linear regression was used, �CEC could be best estimated by organic carbon plus clay content plus ECEC (R2 = 0.77, P < 0.001). To ascertain whether exchangeable Al (or exchange acidity) would contribute to buffer capacity in soils with less variable charge, soils of relatively low organic carbon (<2.5%) were considered. For the 33 soils with <2.5% organic carbon, �CEC was still the major determinant of buffer capacity (r2 = 0.76, P <0.001), although inclusion of exchange acidity in a multiple regression with �CEC significantly increased the variance accounted for (R2 = 0.80, P < 0.001). Of the soil properties that could be routinely measured, a multiple regression equation combining organic carbon, clay content and exchange acidity accounted for 85% of the variance in buffer capacity, with organic carbon being the most important.

Long-term Effects of the Continuous Cultivation of a Tropical Ultisol in Southwestern Nigeria

SUMMARYContinuous cropping of a tropical Ultisol with or without nitrogen fertilizer increased soil acidification and reduced soil organic matter and productivity. Addition of nitrogen fertilizer failed to increase yields. This was apparently due to the decline in soil pH, an increase in the amount of soluble aluminium, and consequent inefficient utilization of added nutrients. Continuous use of ammonium sulphate as a nitrogen source hastened the development of both surface and subsoil exchange acidity.

DEEP PLOWED SOLONETZIC AND CHERNOZEMIC SOILS: I. TILTH AND PHYSICOCHEMICAL FEATURES OF THE CULTIVATED LAYER

Micromorphological, chemical, mineralogical and physical properties of deep plowed and conventionally tilled soils were evaluated at five sites in east-central Alberta. Soil properties, as they relate to soil classification and seedbed tilth, were determined. Deep plowing resulted in the development of a unique soil fabric in Ap horizons which, relative to conventionally tilled soils, had characteristics tending towards higher salinity, sodicity, pH, clay, smectite and strength and lower exchange acidity, total C, total N, available moisture, stability and plasticity. Landscapes dominated by Solonetzic soils responded differently to deep plowing than landscapes where significant areas of Chernozemic soils were present [Formula: see text]. Solonetzic landscapes tended towards significantly higher salinity, sodicity and strength in Ap horizons than Chernozemic landscapes. Key words: Tilth, deep plowing, soil classification, reclamation