Mineral concentrations of forages and soils in Benue State,Nigeria. I. Macrominerals and forage in vitro organic matter digestibility and crude protein concentrations

Abstract

Macromineral composition of different forage species and soils and forage in vitro organic matter digestibility (IVOMD) and crude protein concentrations in three agricultural zones of Benue State were studied. The zones consisted of Tiv zone (Zone A), Igala zone (Zone B), and Idoma zone (Zone C), each of which was made up of three sites. Site I was Fulani cattle migration routes across the state, site II represented grazing sites within home proximity, and site III were grazing reserves. Grazing animals were followed and forages corresponding to that consumed by them, and the corresponding soil samples were collected during the peak of the dry season (December‐January) and analyzed for nutrient composition. Forage IVOMD ranged from 21% to 79%, with values obtained in grass being lowest due to pronounced overmaturity. Only 10% of forage samples (exclusively from grasses), showed protein levels below the critical value of 7%. Most forage samples, as well as their corresponding soil samples were sufficient in calcium (Ca), magnesium (Mg), and potassium (K) concentrations. Soil concentrations of Ca, Mg, and K were particularly high compared to critical requirements in all the zones studied. Approximately 94% and 76% of forages were deficient in phosphorus (P) and sodium (Na), respectively, and the deficiencies were similar in all classes of forage and sites of study for each of the zones investigated. Results of forage‐soil relationships indicated low and nonexisting correlations; therefore soil analyzes are not of great importance in the assessment of available macromineral supplies to grazing livestock. The macrominerals most needed for supplementation of grazing livestock during the dry season are P, Na, and K.     

Mineral concentrations of forages grazed by small ruminants in the wet season in benue state,Nigeria. II. Trace minerals and forage crude protein

Abstract

A total of 71 forage samples were analyzed for trace mineral and crude protein concentrations in three Agricultural zones of Benue State, Nigeria. The zones consisted of the Northern, Eastern, and Central zones, each of which was made up of four Local Government Areas. In each Local Government Area, grazing animals were followed and forages corresponding to those consumed were collected during the peak of the wet season (June) and analyzed for the nutrient composition. Deficiencies were observed in copper (Cu) and cobalt (Co) concentrations in all classes of forage, and in forage Cu and zinc (Zn) in all Local Government Areas in the Northern zone. A higher (P<0.05) forage Cu concentration was observed in legumes compared to other classes of forage in the Eastern zone. Concentrations of iron (Fe) and manganese (Mn) were considered adequate and their contents were not affected (P>0.05) by class of forage or Local Government Areas. In the Eastern zone, the contents of selenium (Se) in grass and tree leaf hay were higher compared to leguminous forage, which in turn was higher compared to Se concentrations in crop wastes. Only about 18% of total forage samples showed protein concentrations below the critical value of 7%. Supplementation of Cu, Zn, and Co would seem to be necessary in the Northern zone, and to a lesser extent in the Eastern zone for optimum productivity of grazing animals.     

Mineral Concentrations of Cool Season Pasture Forages in North Florida During Winter-Spring Grazing Season. I. Macrominerals and Forage Organic Constituents

Two experimental late fall-winter-spring grazing studies, each lasting two years, were conducted at the North Florida Research and Education Center (NFREC), Marianna, Florida to evaluate the organic constituents and macromineral concentrations of annual cool season pasture forages grazed by growing beef cattle. Eight 1.32 ha fenced pastures or paddocks were divided into two pasture land preparation/planting methods, four pastures for the sod seeding treatments and four for the prepared seedbed treatments. These pastures were planted with two different forage combinations: rye/oats mix with or without ryegrass for the first two years (Study 1), and oats with ryegrass or ryegrass only for the last two years (Study 2). Each of the four forage/land preparation combination treatments was assigned to two pastures each year, thereby giving two replicates per year. Forage samples were collected at the start of grazing and twice monthly thereafter until the end of grazing season for each year, pooled by month, and were analyzed for calcium (Ca), phosphorus (P), sodium (Na), potassium (K), magnesium (Mg), dry matter (DM) yield, crude protein (CP), and in vitro organic matter digestibility (IVOMD). Blood plasma samples were also collected from the tester cattle during the spring season of year 2 of Study 2 and were analyzed for Ca, P, and Mg. Month differences were observed in forage concentrations of P and K (P < 0.0001), and Mg (P < 0.05) in both studies, Ca (P < 0.01) in Study 1 only, and Na (P < 0.05) only in Study 2. Year affected P, K, and Mg concentrations in Study 1 and Ca, P, and Na concentrations in Study 2. In Study 2, forage type by month interactions on Ca, K, and Mg concentrations were noticed (P < 0.01). Forage Ca was lower (P < 0.05) than the critical level for all months from the oat plus ryegrass pastures, and for early winter months and late spring months from ryegrass only pasture. Forage Na concentrations were consistently low throughout the grazing season and unaffected by forage type or land cultivation methods used in both studies. Low Mg concentrations of both forage types in Study 2 (also with high K concentrations) were indicative of a potential risk of grass tetany (hypomagnesemia) for grazing ruminants. Forage DM yields were highly variable with fluctuations among the experimental months and were found to be highest in the spring months, with decreasing yields towards the end of the grazing season in both studies (P < 0.0001). The CP concentrations were greater than the required levels and both CP and IVOMD decreased gradually by month in both studies (P < 0.0001). Normal blood plasma concentrations of Ca and P obtained were indicative of a good overall status of these minerals in the animal's body. Plasma Mg concentrations were slightly above the critical level for cattle from both forage types. In summary, the macrominerals most likely to be deficient in North Florida during the cool season would be Ca, Na, and Mg. Special attention should be given to supplementation of Mg since forages reflected a marginal deficiency of this mineral and high K concentrations were found.     

A simple wet chemical extraction procedure to characterize soil organic matter (SOM). I. application and recovery rate

Abstract

The knowledge of soil organic matter (SOM) composition is important for research in soil science. This is why two classical wet chemical extraction procedures were tested and combined to characterize SOM. Twenty‐five samples from typical forest and arable soils in Schleswig‐Holstein, Northwest Germany, were investigated in the laboratory. Lipids were extracted using a pre‐step method. Several polysaccharide fractions were extracted sucessively with inorganic acids in a litter compound analysis (LCA). Proteins and lignins were determined in the bulk soil sample. In a humic compound analysis (HCA), fulvic and humic acids were extracted in the classical way with NaOH, and the non‐humic substances were removed with the aid of the “Sulfacetolysis” from the residues (= usually “humins")‐ The combination of these two wet chemical extraction proce dures (LCA and HCA) permitted quantitative estimations of the SOM composition in several soil horizons. The LCA method produced a better recovery rate (104%±4%) than the HCA methode (95%±15%). The litter compound/humic compound ratio of both analyses, and the combination of both correlated with visible humification grades in a significant way (r = ‐0.733 to ‐0.742***). LCA may be sufficient for solving special pedogenetic problems, because of its high recovery rate and the strong correlation between LCA and HCA.     

Colluvisols under cultivation in Schleswig-Holstein. 2. Carbon distribution and soil organic matter composition

Soils under intensive cultivation have altered due to water erosion. This study was conducted to determine whether soil organic matter (SOM) composition of the colluvial source (Ap horizons) differs from the colluvial sink (M horizons). The SOM of a sandy Catena with erodic Cambisols and colluvic soils (Colluvisols) in Schleswig-Holstein, Northwest Germany, was investigated. A wet chemical analysis was combined with CPMAS ¹³C-NMR spectroscopy. In one case a significant correlation between the SOM composition of the Ap horizon of the erodic Cambisol and the M horizon of the Colluvisol was high (r² = 0.904^-), whereas the correlation for the other set was much weaker (r² = 0.640*). Two possible paths of pedogenesis are discussed. About 70% of the SOM of the colluvial source is decomposed during translocation or after deposition. A selective preservation or new formation of humins in the M material is probable. These humins contain, obviously, large amounts of polysaccharides, which were not detected by the wet chemical analysis. Further investigations of colluvic and erodic soils are necessary in order to specify the SOM quality and its possible modification due to soil translocation and accumulation.     

Soil microbial biomass and organic matter composition in soils under cultivation

To determine whether there is a relationship between the composition of soil organic matter and the activity of the soil microbial biomass, the composition of the organic matter in 12 typical arable soils in Northwest Germany was investigated by wet chemical analysis and CPMAS cross polarization magic angle spinning ¹³C-NMR spectroscopy. The data were correlated with the microbial biomass as estimated by substrate-induced respiration. A strong correlation between the microbial biomass and alkylic C compounds was observed (r=-0.960^***). Recalcitrant substances were enriched in this fraction, which were classified as humic acids according to the wet chemical procedure. The microbial decomposition of these humic acids is probably retarded, due to their chemical structure and/or physical bonding, when the soil microbial biomass activity is limited.     

Tillage practice influences on the physical protection, bioavailability and composition of particulate organic matter

 This study was conducted to determine whether separation of particulate organic matter (POM) that is biologically labile from aggregate entrapped material improves the usefulness of POM as an index of soil C and N dynamics. The effects of conventional (CT) and no-tillage (NT) practices on POM were assessed using soils from three 10-year trials in Illinois. Loose and occluded POM in the 0–5 cm depth were separated from 1994 samples. Use of NT practices increased C and N contents at 0–5 cm relative to CT practices and those increases were most apparent in the occluded POM fraction. The correlation between total POM-N and potentially mineralizable N (PMN) was stronger than that between PMN and either the loose or occluded-POM fractions. In 1995, both the microbial biomass, estimated as chloroform-labile C (CFEC), and PMN were correlated with POM-C and N, but the relationship was weak when data (from different tillage and depth combinations) were not treated in aggregate. POM-C and CFEC were most strongly correlated in surface depths and in CT treatments. In NT 0–5 cm samples, PMN contents were similar (≈27 mg N kg^–1 soil) at all sites despite notable differences in POM-N concentrations; PMN was not related to POM-N in CT samples. There was no consistent relationship between PMN and POM-N contents in 5–30 cm samples. DRFTIR spectra indicated that carbohydrates were most abundant in POM at 0–5 cm. Relatively low PMN rates and enrichment of polysaccharides in POM in the sicl soil suggest that physical protection of labile organic substrates was more important at that site than at sites with lighter textured soils. Improved fractionation and incubation techniques and alleviation of laboratory artifacts will improve our ability to relate POM quantity, distribution and composition to biologically mediated C and N dynamics occurring in the field. Received: 2 December 1999     

Influence of lipid physical state on the in vitro digestibility of emulsified lipids

The objective of this study was to investigate the influence of the physical state of emulsified lipids on their in vitro digestibility by pancreatic lipase. A 10 wt % tripalmitin oil-in-water emulsion stabilized by sodium dodecyl sulfate (0.9 wt % SDS) was prepared at a temperature (>70 degrees C) above the melting point of the lipid phase (T(m) approximately 60 degrees C). A portion of this emulsion was cooled to a temperature (0 degrees C for 15 min) well below the crystallization temperature of the emulsified lipid (T(c) approximately 22 degrees C) and then warmed to 37 degrees C so as to have completely solid lipid particles. Another portion of the emulsion was directly cooled from 70 to 37 degrees C (which is above the T(c)) to have completely liquid (supercooled) lipid particles. Pancreatic lipase (8 mg/mL) and bile extract (5.0 mg/mL) were then added to each emulsion at 37 degrees C, and the evolution of the particle charge, particle size, appearance, and free fatty acid release were measured over a period of 2 h. It was found that the rate and extent of lipid digestion were higher in the emulsion containing liquid particles but that appreciable lipid digestion still occurred in the emulsion containing solid particles (i.e., >35% lipid digestion after 2 h). These results may have important consequences for controlling the digestion rate of lipids or for developing solid lipid particle delivery systems for lipophilic functional components.     

No-till effects on organic matter, pH, cation exchange capacity and nutrient distribution in a Luvisol in the semi-arid subtropics

No-till (NT) system for grain cropping is increasingly being practised in Australia. While benefits of NT, accompanied by stubble retention, are almost universal for soil erosion control, effects on soil organic matter and other soil properties are inconsistent, especially in a semi-arid, subtropical environment. We examined the effects of tillage, stubble and fertilizer management on the distribution of organic matter and nutrients in the topsoil (0–30 cm) of a Luvisol in a semi-arid, subtropical environment in southern Queensland, Australia. Measurements were made at the end of 9 years of NT, reduced till (RT) and conventional till (CT) practices, in combination with stubble retention and fertilizer N (as urea) application strategies for wheat (Triticum aestivum L.) cropping.

In the top 30 cm depth, the mean amount of organic C increased slightly after 9 years, although it was similar under all tillage practices, while the amount of total N declined under CT and RT practices, but not under NT. In the 0–10 cm depth, the amounts of organic C and total N were significantly greater under NT than under RT or CT. No-till had 1.94 Mg ha⁻¹ (18%) more organic C and 0.20 Mg ha⁻¹ (21%) more total N than CT. In the 0–30 cm depth, soil under NT practice had 290 kg N ha⁻¹ more than that under the CT practice, most of it in the top 10 cm depth. Microbial biomass N was similar for all treatments. Under NT, there was a concentration gradient in organic C, total N and microbial biomass N, with concentrations decreasing from 0–2.5 to 5–10 cm depths.

Soil pH was not affected by tillage or stubble treatments in the 0–10 cm depth, but decreased significantly from 7.5 to 7.2 with N fertilizer application. Exchangeable Mg and Na concentration, cation exchange capacity and exchangeable Na percentage in the 0–10 cm depth were greater under CT than under RT and NT, while exchangeable K and bicarbonate-extractable P concentrations were greater under NT than under CT.

Therefore, NT and RT practices resulted in significant changes in soil organic C and N and exchangeable cations in the topsoil of a Luvisol, when compared with CT. The greater organic matter accumulation close to the soil surface and solute movement in these soils under NT practice would be beneficial to soil chemical and physical status and crop production in the long-term, whereas the concentration of nutrients such as P and K in surface layers may reduce their availability to crops.     

Evaluating baseline data for trace elements,pH, organic matter content,and bulk density in agricultural soils in Nigeria

Agricultural soil samples were collected about 1 km apart over 21 km from 32 tilled/cultivated plots of yam, rice, and cassava in urban, rural, and the derelict Enyibga lead-zinc mine (EM) in the Abakaliki area, Nigeria during the rainy season in September, 1992. In the derelict mine, mean elemental contents increased in the order Cd < Ni < Cu < Mn < Pb < Zn; while in the urban, rural, and all soils combined, the order increased as follows: Cd < Cu < Ni < Pb < Zn < Mn. The overall mean distribution of all soils shows Mn and Zn to approach and exceed toxic levels, respectively. In all soils, the total mean concentrations of Cu and Ni are well below toxic levels. The Abakaliki area is less likely to be subjected to Cd-contaminated soils. Pb was excessively high at EM and, moderately high at Mgbowo Street in the urban area, but very less so in the rural areas. The rural agricultural areas of Agbaja, Nkwaegu, and Amaegu, including the isolated Ezza Road as well as the peripheral Expressway had relatively lower levels of heavy metals, pH and organic matter content than the urban conglomeration of Mile 50, Mgbowo Street, and Azuiyiokwu including the derelict mining village of Enyigba and EM; except that Ezza Road had pH and organic matter as high as the densely populated urban cultivated areas. The relationship between bulk density and organic matter was highly dependent on pH.     

The response of organic matter mineralisation to nutrient and substrate additions in sub-arctic soils

Global warming in the Arctic may alter decomposition rates in Arctic soils and therefore nutrient availability. In addition, changes in the length of the growing season may increase plant productivity and the rate of labile C input below ground. We carried out an experiment in which inorganic nutrients (NH₄NO₃ and NaPO₄) and organic substrates (glucose and glycine) were added to soils sampled from across the mountain birch forest-tundra heath ecotone in northern Sweden (organic and mineral soils from the forest, and organic soil only from the heath). Carbon dioxide production was then monitored continuously over the following 19 days. Neither inorganic N nor P additions substantially affected soil respiration rates when added separately. However, combined N and P additions stimulated microbial activity, with the response being greatest in the birch forest mineral soil (57% increase in CO₂ production compared with 26% in the heath soil and 8% in the birch forest organic soil). Therefore, mineralisation rates in these soils may be stimulated if the overall nutrient availability to microbes increases in response to global change, but N deposition alone is unlikely to enhance decomposition. Adding either, or both, glucose and glycine increased microbial respiration. Isotopic separation indicated that the mineralisation of native soil organic matter (SOM) was stimulated by glucose addition in the heath soil and the forest mineral soil, but not in the forest organic soil. These positive ‘priming’ effects were lost following N addition in forest mineral soil, and following both N and P additions in the heath soil. In order to meet enhanced microbial nutrient demand, increased inputs of labile C from plants could stimulate the mineralisation of SOM, with the soil C stocks in the tundra-heath potentially most vulnerable.     

Chemical composition, in vitro fermentation characteristics, and in vivo digestibility responses by dogs to select corn fibers

The objective was to examine the chemical composition, in vitro fermentation characteristics, and in vivo digestibility responses of fiber-rich corn coproducts resulting from corn wet milling. Native corn fibers, native corn fibers with fines, hydrolyzed corn fibers, and hydrolyzed extracted corn fibers were analyzed chemically and their capacity to produce short-chain fatty acids determined. Ash content was low (<1.2%), crude protein content varied little, but fat and fiber concentrations varied widely. Most fiber was in the insoluble form, with glucose being predominant followed by xylose. Total short-chain fatty acid production ranged from 211.6 to 699.52 micromol/g of dry matter, whereas branched-chain fatty acid production was low. Four corn fibers (native and processed) were included in a canine diet matrix at the 7% inclusion level. Nutrient digestibility, food intake, and fecal characteristics were not affected by corn fiber inclusion in canine diets, suggesting that they should be considered as potential dietary fiber sources in dog foods.     

Soil organic matter and nutrient accumulation in areas under intensive management and swine manure application

Purpose

Land use change and soil management are frequently associated to land degradation and soil organic matter (SOM) losses in tropical regions. In Brazil, in order to avoid this process, different management strategies have been applied, such as no-tillage and agricultural disposal of swine manure (SM). This study was carried out to evaluate the quantity and quality of SOM, as well as the occurrence of nutrient accumulation in soils of areas under contrasting management systems that have received consecutive applications of SM over the last decades in Brazil.

Materials and methods

Five land uses were sampled: native vegetation (NV), pasture with SM application (PA + SM), no-tillage with SM application (NT + SM), no-tillage (NT), and conventional tillage with SM application (CT + SM). Soil organic carbon (SOC), N, labile C, C management index (CMI), P, Ca²⁺, Mg²⁺, K⁺, Al³⁺, Fe, Zn, Mn, Cu, and H + Al were quantified.

Results and discussion

Except for PA + SM, the agricultural land uses caused decreases in SOC contents comparing to NV. PA + SM showed the highest C stocks, 138.9?±?3.4 Mg ha^?1 down to 0.4 m. The application of SM can be associated to the greater C stocks in PA + SM, NT + SM, and CT + SM and to the higher N contents in all land uses under this practice. Land uses which receive higher rates of swine manure application (PA + SM and CT + SM) have shown CMI greater than 100. However, this practice is associated to the accumulation of P, Cu, Na, and Zn in these soils.

Conclusions

The SM application is associated to improvement on C stocks and SOM quality in area under pasture, no-tillage, and conventional tillage in Paraná State, Brazil. However, this practice is the main driver of nutrient accumulation in these areas.

     

Characterizing Farmer Users and Nonusers of Mass Media as Channels of Agricultural Information in Benue State,Nigeria

This study characterized farmer users and nonusers of mass media as channels of agricultural information. A structured interview was used to obtain data from 316 randomly selected farmers in Benue State, Nigeria. The data were subjected to discriminant analysis and the following socioeconomic characteristics significantly differed at a 5% level of probability between users and nonusers of mass media (and their F-ratio values): education (6.30), income (5.12), gender (4.84), and socioeconomic status (4.83). Farmer users of mass media are therefore those who have good level of education, belong to a relatively high income bracket, and are typically male and of a relatively high socioeconomic status. Farmers’ socioeconomic characteristics should be considered in planning mass media usage in agricultural information dissemination.     

Effect of meat cooking on physicochemical state and in vitro digestibility of myofibrillar proteins

The effect of meat cooking was measured on myofibrillar proteins from bovine M. Rectus abdominis. The heating treatment involved two temperatures (100 degrees C during 5, 15, 30, and 45 min and 270 degrees C during 1 min). Protein oxidation induced by cooking was evaluated by the level of carbonyl and free thiol groups. Structural modifications of proteins were assessed by the measurement of their surface hydrophobicity and by their aggregation state. With the aim of evaluating the impact of heat treatment on the digestive process, myofibrillar proteins were then exposed to proteases of the digestive tract (pepsin, trypsin, and alpha-chymotrypsin) in conditions of pH and temperature that simulate stomach and duodenal digestion. Meat cooking affected myofibrillar protein susceptibility to proteases, with increased or decreased rates, depending on the nature of the protease and the time/temperature parameters. Results showed a direct and quantitative relationship between protein carbonylation (p<0.01) and aggregation (p<0.05) induced by cooking and proteolytic susceptibility to pepsin. However, no such correlations have been observed with trypsin and alpha-chymotrypsin.     

Thermal stability and composition of mineral-bound organic matter in density fractions of soil

Heavy density fractions of soil contain organic matter tightly bound to the surface of soil minerals. The chemical composition and ecological meaning of non-metabolic decomposition products and microbial metabolites in organic–mineral bonds is poorly understood. Therefore, we investigated the heavy fraction (density > 2 g cm^–3) from the topsoil of a Gleysol (Bainsville, Ottawa, Canada). It accounted for 952 g kg^–1 of soil and contained 19 g kg^–1 of organic C. Pyrolysis-field ionization mass spectra showed intensive signals of carbohydrates, and phenols and lignin monomers, alkylaromatics (mostly aromatic) N-containing compounds, and peptides. These classes of compound have been proposed as structural building blocks of soil organic matter. In comparison, the light fraction (density > 2 g cm^–3) was richer in lignin dimers, lipids, sterols, suberin and fatty acids which clearly indicate residues of plants and biota. To confirm the composition and stability of mineral-bound organic matter, we also investigated the heavy fraction (density > 2.2 g cm^–3) from clay-, silt- and sand-sized separates of the topsoil of a Chernozem (Bad Lauchstädt, Germany). These heavy size separates differed in their mass spectra but were generally characterized by volatilization maxima of alkylaromatics, lipids and sterols at about 500°C. We think that the observed high-temperature volatilization of these structural building blocks of soil organic matter is indicative of the organic–mineral bonds. Some unexpected low-temperature volatilization of carbohydrates, N-containing compounds, peptides, and phenols and lignin monomers was assigned to hot-water-extractable organic matter which accounted for 7–27% of the carbon and nitrogen in the heavy fractions. As this material is known to be mineralizable, our study indicates that these constituents of the heavy density fractions are degradable by micro-organisms and involved in the turnover of soil organic matter.     

Forms and profile distribution of potassium in typical soils of the lower Benue Valley of Nigeria

Abstract

Six profiles, derived from Precambrian Basement Complex rocks (mainly gneiss), Cretaceous sediments (mainly shale and sandstone), and Quaternary alluvium, and which are typical of the major agricultural soils in the Lower Benue Valley (Nigeria) were studied with the objective to determine their overall potassium (K) reserves and any relationship between these and other soil properties including their parent materials. Total K in the soils varies from 0.13–27.1 g kg^‐1 with average 6.64 g kg‐¹. This correlates positively with the clay, and negatively with the sand contents of the soils and is also influenced by their parent materials. The order of abundance according to parent material is: alluvium‐ > Basement Complex (gneiss)‐ ≈ shale‐ > sandstone‐derived soils. The concentrations of readily available K (RAK) in the soils are quite low, accounting for only between 0.30 and 7.8% of the total K in the soils and less than 4.0% of their exchange capacities. Based on critical limits established for many Nigerian soils, the soils derived from sandstone are clearly deficient in RAK, while soils developed from gneiss, shale and alluvium parent materials have moderate to sufficient levels for a wide range of crops. Non‐exchangeable or moderately available K (MAK) in the soils is also relatively low (0.020–8.59 mmol_c kg^‐1); while the sandstone‐derived soils have the least MAK, the alluvial soils have the most levels. However, the potassium supplying power (KSP) of the soils may be considered to be generally high. Although this bears no particular relationship to soil parent materials, the sandstone‐derived soils have the lowest KSP. The bulk of the total K reserves in the soils (55–88%) exists as difficultly available or structural K (DAK). The alluvial soils first, then the gneiss‐ and shale‐derived soils next have the highest contents of DAK, while the highly weathered sandstone soils have the lowest. Simple correlation analysis shows that, irrespective of parent material and K form, clay content and CEC are the most important soil properties influencing the overall K supplying status of these soils. It is concluded that in major agricultural soils of the Lower Benue Valley of Nigeria K exists mostly in the lattice structures of K‐bearing minerals, with accumulations in the subsurface horizons. Its plant‐available or supplying status is low on sandstone‐derived soils and moderate to sufficient on soils derived from Basement Complex rocks, shales and alluvium.     

Properties and composition of soil organic matter in forest and arable soils of Schleswig-Holstein: 1. Comparison of morphology and results of wet chemistry,CPMAS-13C-NMR spectroscopy and pyrolysis-field ionization mass spectrometry

Properties and composition of 25 soil samples (0.8–51% C_org) were determined by morphology, wet chemistry, CPMAS-¹³C-NMR-spectroscopy and pyrolysis-field ionization mass spectrometry (Py-FIMS). The recovery rate of organic carbon was 102% (±15%). The correlation between the litter compound/humic compound ratio and humification grade, estimated with morphological observations, was strong (r² = 0.502^***). A typical classification of horizons (L, O, H, Ah+M) with regard to organic compounds (wet chemistry and ¹³C-NMR) was not always significant. The pyrolysis-mass spectra confirmed and extended on the basis of molecular chemical structures the results of wet chemistry, especially with polysaccharides, nitrogen compounds, lignin, lipids and alkylaromatics (r² = 0.818–0.937^***). A correlation between the NMR-aliphatics, the humic compounds isolated by wet chemistry, and the long-chain aliphatic carbon units in the pyrolysis-mass spectra was established.     

Application of thermometric titrations to the study of soil organic matter. I. Simple polyelectrolytes

An introduction to the technique of thermometric titrimetry is provided and its special potentialities for the study of humic substances are discussed. As a prelude to the investigation of the complicated humic systems, the relatively simple polyelectrolytes, PAA and PMA, were first studied. Thermometric titration of these polymeric acids with sodium hydroxide solution gave good end points. Thermometric titration of the salts of these acids with various transition metal ions gave end point breaks corresponding stoichiometrically to charge neutralization of the polyelectrolyte. These thermometric titrations involving the transition metal ions are compared with the corresponding nephelometric titrations.     

Near‐infrared spectroscopy can predict the composition of organic matter in soil and litter

The usefulness and limitations of near‐infrared reflectance spectroscopy (NIRS) for the assessment of several soil characteristics are still not sufficiently explored. The objective of this study was to evaluate the ability of visible and near‐infrared reflectance (VIS‐NIR) spectroscopy to predict the composition of organic matter in soils and litter. Reflectance spectra of the VIS‐NIR region (400–2500 nm) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by ¹³C‐CPMAS‐NMR spectroscopy. A modified partial least‐square method and cross‐validation were used to develop equations for the different constituents over the whole spectrum (1st to 3rd derivation). Near‐infrared spectroscopy predicted well the C : N ratios, the percentages of O‐alkyl C and alkyl C, the ratio of alkyl C to O‐alkyl C, and the sum of phenolic oxidation products: the ratios of standard deviation of the laboratory results to standard error of cross‐validation (RSC) were greater than 2, the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater than 0.9. Satisfactorily (0.8 ≤ a ≤ 1.2, r ≥ 0.8, and 1.4 ≤ RSC ≤ 2.0) assessed were the contents of C, N, and production of DOC, the percentages of carbonyl C and aromatic C and the ratio of alkyl C to aromatic C. However, the N‐mineralization rate and the microbial biomass were predicted unsatisfactorily (RSC < 1.4). The good and satisfactory predictions reported above indicate a marked usefulness of NIRS in the assessment of biological and chemical characteristics of soils and litter.