Nitrogen mineralization and its controlling factors in various kinds of temperate humid-zone soils

The N mineralization capacity of 41 temperate humid-zone soils of NW Spain was measured by aerobic incubation for 15 days at 28°C and 75% of field capacity. The main soil factors affecting organic N dynamics were identified by principal components analysis. Ammonification predominated over nitrification in almost all soils. The mean net N mineralization rate was 1.63% of the organic N content, and varied according to soil parent materials as follows: soils on basic and ultrabasic rocks < soils over acid metamorphic rocks < soils developed over sediments < soils over acid igneous rocks < soils on limestone. The N mineralization capacity was lower in natural soils than in cropped soils or pastures. The accumulation of organic matter (C and N) seems to be due to poor mineralization which was caused, in decreasing order of importance, by high exchangeable H-ion levels, high Al and Fe gel contents and, to a lesser extent (though more markedly in cropped soils), by silty clay texture and exchangeable Al ions.     

Assay of nitrogen supplying capacity of tropical rice soils

Summary The nitrogen supplying capacity of 39 wetland rice soils evaluated by two anaerobic incubation methods and six chemical methods was compared with N uptake of IR 26 rice grown on these soils under flooded conditions in a greenhouse pot study. The uptake of N by rice correlated highly with the N supplying capacity determined by anaerobic incubation methods involving incubation of soils at 30°C for 2 weeks (r=0.84^**) or at 40°C for 1 week (r=0.82^**) as well as with the organic carbon (r=0.82^**) and total N (r=0.84^**) contents of soils. Among the chemical indexes, available N determined by the oxidative release of soil N by alkaline permanganate, acid permanganate, acid dichromate and hydrogen peroxide also provided good index of soil N availability to rice. According to these results soil organic carbon and total N contents seem to be good indexes of available nitrogen in tropical wetland rice soils.     

Nitrification in some tropical soils

Summary Nitrification of soil N in 8 mineral and 2 histosols having a wide range in pH (3.4 to 8.6), organic C (1.22 to 22.70%) and total N (0.09 to 1.20%) was studied by measuring nitrate fromation under aerobic incubation of the soil samples at 30°C for 4 weeks. The amounts of NO₃-N produced in the soils varied from 0 to 123 μg/g of soil. Soil N in the two acid sulfate soils and one other acid soil did not nitrify under conditions that stimulate nitrification. Soils having pH more than 6.0 nitrified at a rapid rate and released NO₃-N ranging from 98 to 123 μg/g. The two organic soils differed considerably in their capacity to nitrify though the total amounts of mineral N released were similar in these soils. The amounts of NO₃-N formed in the soils was highly positively correlated with the soil pH but was not significantly correlated with the organic C of total N content of the soils. Statistical analysis also showed that nitrate formation was not significantly correlated with soil pH in soils having pH higher than 6.0.     

Variations in soil culturable bacteria communities and biochemical characteristics in the Dongkemadi glacier forefield along a chronosequence

The variations in the soil culturable bacterial communities and biochemical parameters of early successional soils from a receding glacier in the Tanggula Mountain were investigated. We examined low organic carbon (C) and nitrogen (N) contents and enzymatic activity, correlated with fewer bacterial groups and numbers in the glacier forefield soils. The soil pH values decreased, but the soil water content, organic C and total N significantly increased, along the chronosequence. The soil C/N ratio decreased in the early development soils and increased in the late development soils and it did not correlate with the soil age since deglaciation. The activities of soil urease, sucrase, protease, polyphenol oxidase, catalase, and dehydrogenase increased along the chronosequence. The numbers of culturable bacteria in the soils increased as cultured at 25°C while decreased at 4°C from younger soils to older soils. Total numbers of culturable bacteria in the soils cultured at 25°C were significantly positively correlated to the soil total N, organic C, and soil water content, as well as the activities of soil urease, sucrase, dehydrogenase, catalase, and polyphenol oxidase. We have obtained 224 isolates from the glacier forefield soils. The isolates were clustered into 28 groups by amplified ribosomal DNA restriction analysis (ARDRA). Among them, 27 groups and 25 groups were obtained from the soils at 25°C and at 4°C incubation temperatures, respectively. These groups are affiliated with 18 genera that belong to six taxa, viz, Actinobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, Alphaproteobacteria, and Betaproteobacteria. The dominant taxa were Actinobacteria, Gammaproteobacteria, and Bacteroidetes in all the samples. The abundance and the diversity of the genera isolated at 25°C incubation temperature were greater than that at 4°C.     

Soil C and N dynamics within a precipitation gradient in Mediterranean eucalypt plantations

Soil C and N dynamics were evaluated in five eucalypt plantations within a precipitation gradient (500–2,000 mm) in Portugal. Soil physical and chemical properties, total and labile (particulate organic matter, hydrolyzable, hot water soluble and microbial) soil C and N pools, and C and N mineralization were measured to characterize the C and N dynamics and their controlling factors within this gradient. Contents of total and labile soil organic C and N were positively correlated with the mean annual precipitation. A similar relationship was observed for net N mineralization (anaerobic and long-term aerobic incubation), gross N mineralization (¹⁵N isotope dilution technique) and C mineralization. In contrast, rates of C and N mineralization (per unit of C and N) were higher in the driest sites due to their higher proportion of particulate organic matter C. Net and gross N mineralization were strongly correlated and showed similar controlling factors (mean annual precipitation, total and labile C and N and extractable P contents), suggesting that net N mineralization during long-term aerobic incubation reflects gross N transformations. Although, gross NO₃–N production and gross NO₃–N immobilization were observed in all sites, net nitrification in the drier sites was not observed in the first weeks of the study. Our results suggest that, under Mediterranean conditions, mean annual precipitation is the major factor determining the C and N dynamics in soils with Eucalyptus plantations.     

Screening legume green manures as nitrogen sources to succeeding non-legume crops

Legumes managed as green manures provide a good alternative to the use of commercial N-fertilizer for non-legume crop production. A laboratory procedure based on the aerobic incubation (35 °C) of soil samples taken from plots with legumes incorporated was proposed for predicting the N supplying potential of legumes to succeeding non-legume crops. This procedure was evaluated by comparing the amount of inorganic N determined in the soil samples after incubation with N content of aboveground dry matter of maize or with inorganic N found in the soil of an adjacent fallow plot. The soil samples (0.00 to 0.15 m and 0.15 to 0.30 m) were obtained from two field experiments conducted in similar soils of the Cerrado Region of central Brazil during 1984–85 and 1986–87. Although incubation results were affected by the different pretreatments, soil samples prepared and incubated as soon as possible after being taken from the field gave the best correlations. The most convenient incubation procedure was the one-week aerobic incubation of samples previously oven dried at 50°C. The results obtained by this procedure were significantly correlated with N content in aboveground dry matter of maize and with the inorganic N accumulated in an adjacent fallow plot.     

Impact of chemical composition of legume residues and initial soil pH on pH change of a soil after residue incorporation

Reports on the effect of organic matter addition on soil pH have been contradictory. This study examined the effect of applying legume residues differing in concentrations of N (4.3-45.5 mg g^-1) and excess cations/organic anions (0.22–1.56 mmol g^-1) on pH change of five soils differing in initial pH (3.60–5.58 in 0.01 M CaCl₂) under sterile and non-sterile conditions. Addition of the legume residues at a level of 1% soil weight increased the pH of all soils by up to 2 units after incubation for 35 and 100 d under non-sterile conditions. Exceptions were the Lancelin (initial pH 5.06) and Kellerberin (pH 5.58) soils with addition of clover roots (excess cations 22 cmol/kg) for 100 d where soil pH decreased by 0.13–0.15 units as compared to the control. The amounts of alkalinity produced in soil correlated positively with concentrations of excess cations and total nitrogen of the added legume residues, and negatively with the initial pH of the soil. When soil was fumigated with chloroform during incubation, similar trends of soil pH changes and alkalinity production, due to legume residues addition, were displayed but the effects of the residue on alkalinity production in the Wodjil and Lancelin soils were much less than under non-sterile conditions. Direct shaking of soil with the residues under sterile conditions increased the amount of alkalinity in the soils with initial pH of 3.60–4.54, but not in the soils with initial pH of 5.06 and 5.58. The maximal alkalinity production was less than one third of that produced in the soil after 100 d of incubation under non-sterile conditions. The results suggest that the direction and the magnitude of pH change depend largely on the concentration of organic anions in the residues, initial soil pH and the degree of residue decomposition. The incorporation of crop residues, especially those with high concentrations of excess cations, is recommended in minimizing soil acidification in farming systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

A study of soil nitrogen organic fractions and correlation with yield response of Sudan-sorghum hybrid grass on Quebec soils

Summary Acid-hydrolysable organic nitrogen fractions were determined before and after two crops of Sudan-sorghum hybrid grass grown in a growth chamber on twenty Quebec soils. The relationship between the organic nitrogen fractions and yield response to N fertilizer and N uptake was examined by correlation methods and compared with corresponding relations obtained using incubation and boiling water extraction methods as indices of soil N availability. Mean contributions to total N lost during growth of the two crops were: hydrolysable NH ₄ ⁺ -N−19%, amino acid N−16% and hexosamine N−2%. The amino acid N, hydrolysable NH ₄ ⁺ -N and total hydrolysable N were significantly correlated with percent yield, log percent yield decrement and N uptake. Better correlations were obtained with the incubation and boiling water extraction methods than with the organic-N fractions. Contribution from Department of Soil Science, Macdonald College of McGill University.     

Microbial Decomposition of Synthetic 14C-Labeled Lignins in Nature: Lignin Biodegradation in a Variety of Natural Materials

Lignin biodegradation in a variety of natural materials was examined using specifically labeled synthetic ¹⁴C-lignins. Natural materials included soils, sediments, silage, steer bedding, and rumen contents. Both aerobic and anaerobic incubations were used. No ¹⁴C-labeled lignin biodegradation to labeled gaseous products under anaerobic conditions was observed. Aerobic ¹⁴C-labeled lignin mineralization varied with respect to type of natural material used, site, soil type and horizon, and temperature. The greatest observed degradation occurred in a soil from Yellowstone National Park and amounted to over 42% conversion of total radioactivity to ¹⁴CO₂ during 78 days of incubation. Amounts of ¹⁴C-labeled lignin mineralization in Wisconsin soils and sediments were significantly correlated with organic carbon, organic nitrogen, nitrate nitrogen, exchangeable calcium, and exchangeable potassium.     

Patern of nitrogen release during decomposition of some green manures in a tropical alluvial soil

Summary The pattern of release of ammonium and nitrate nitrogen during decomposition of glyricidia, sunflower, centrosema, calapagonium and crotolaria under aerobic and anaerobic conditions, in an alluvial soil over a period of 7 weeks was studied. Under aerobic conditions, the NH₄ ⁺–N production reached the maximum after the 4th week. Nitrate-N and total available-N increased in all cases throughout the incubation period except in sunflower. This showed a nitrification inhibitory effect and had a relatively high C/N ratio (11.0) and low total N content (2.8%). In general the increase in NH₄ ⁺–N and NO₃ ^––N was more rapid in the early stages of incubation.Under anaerobic conditions, the production of these nutrients was considerably low. Soil organic matter mineralized faster than the added organic material which started to decompose slowly after sometime. Nitrate-N tend to decrease during incubation attributable to denitrification.     

Prediction of the non-fertilizer N supply of mineral grassland soils

Different methods for estimating the non-fertilizer N supply (NFNS) of mineral grassland soils were compared. NFNS was defined as the N uptake on unfertilized plots. The potential mineralization rate (0–12 weeks), macroorganic matter and active microbial biomass (determined by the substrate-induced respiration method; SIR) were correlated positively with NFNS. The difference between the actual soil organic N or microbial N content (determined by the fumigation incubation method) and their contents under equilibrium conditions ( org. N and MB-N), however, gave the best estimations of NFNS. For field conditions the best estimation for NFNS was: NFNS (kg N ha^–1 yr^–1)=132.3+42.1× org. N (g kg^–1 soil; r=0.80). This method is based on the observation that, under old grassland swards, close relationships exist between soil texture and the amounts of soil organic N and microbial N. These relationships are assumed to represent equilibrium conditions as under old swards under constant management, the gain in soil organic N and microbial N equals the losses. Soils under young grassland and recently reclaimed soils contained less soil organic N and microbial N. In such soils the amounts of organic N and microbial N increase with time, which is reflected in a lower NFNS. The annual accumulation of organic and microbial N gradually becomes smaller until organic N, microbial N and NFNS reach equilibrium. The main advantage of the difference method in comparison with the other methods is its speed and simplicity.FAX no: +31 50337291     

Organic matter composition and degree of humification in lignite-rich mine soils under a chronosequence of pine

In the Lusatian mining district, in the eastern part of the Federal Republic of Germany, organic matter of reclaimed mine soils consists of a mixture of lignite and recently formed soil organic matter (recent carbon). The aim of the study was to investigate the recent carbon accumulation and the degree of humification of a chronosequence of young mine soils under forest. The lignite content of the forest floor, Ai (0–5 cm) and Cv horizons (1 m depth) was determined by ¹⁴CU activity measurements and the structural composition of the organic matter was characterised by ¹³C CPMAS NMR spectroscopy. To obtain a characterisation of the degree of humification, the soil samples were analysed for the content of polysaccharides, proteins, lignin and lipids by wet chemical methods. ¹⁴C activity measurements indicate that at the oldest site, comparable amounts of carbon accumulated in the first few centimetres of the soil profile than in natural forest soils. ¹³C CPMAS NMR spectra of the organic matter in the Ai horizons of the three soil profiles were dominated by aromatic and alkyl carbon species characteristic for lignite, but indicated as well an increasing contribution of carbon species from decomposing plant litter with soil age. When the results from wet chemical analyses were normalised to the total carbon content no changes with age could be noticed. After normalisation of the amount of litter compounds to the recent carbon content, the carbon identified by plant litter compound analysis decreased with increasing depth and increasing age of the soils. After 32 years the values are comparable to those of natural forest soils. These observations were confirmed by increasing degree of lignin alteration with stand age and soil depth. The data of wet chemical analyses complement data obtained by ¹⁴C activity measurements and ¹³C CPMAS NMR spectroscopy and lead to the conclusion that 32 years after reforestation the degree of humification of the soil organic matter is in the same range as those of natural sites. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nitrogen mineralisation potential in calcareous soils amended with sewage sludge

Mineralisation of organic N is an important consideration when determining the annual amount of sewage sludge to be applied to agricultural soils. The mineralisation of sludge organic N was studied in two different textured soils (clayey and sandy soil) treated with aerobic and anaerobic sludge at two different rates (30 and 50 g sludge kg(-1) soil). The mineralisation of sludge organic N was determined during 20 weeks incubation period by analysis of inorganic N produced by a non-leached procedure. Sludge organic N mineralisation was influenced by soil type, organic N mineralisation being greater in the sandy soil (from 30% to 41%) than in the clayey soil (from 13% to 24%). Mineralisation rates decreased rapidly the first two weeks, followed by a slower decrease with time. Although total mineralisation increased with sludge addition rate, net mineralisation decreased with sludge addition rate, probably due to denitrificaton losses. The aerobically treated sludge gave higher mineralisation rates than the anaerobically treated one. The values of N0 and k for treated soils varied depending on the type of sludge and soil.     

Nitrogen release from eucalypt leaves and legume residues as influenced by their biochemical quality and degree of contact with soil

Large areas of short-rotation eucalypt plantations are being established in south-western Australia on land previously used for agriculture. Options for maintaining soil N supply include retention of harvest residues and legume inter-cropping. We evaluated the effects of adding the residues of five legume species and Eucalyptus globulusleaves on inorganic N dynamics in two soils (a Rhodic Ferralsol or red earth and a Haplic Podzol or grey sand) using two modes of residue application in a laboratory incubation experiment (519 days). The time course of net N immobilisation and mineralisation in both soils was strongly influenced by the type and mode of application. Eucalypt leaves caused strong N immobilisation (–7 mg N g^–1 residue-C) over the entire 519-day incubation, whereas for the legume species, N that was eventually immobilised at the start of the incubation, remineralised later to different degrees. Amongst the legumes, largest amounts of N were released from lupin residues (18 mg N g^–1 residue-C) and lowest amounts from field pea (2 mg N g^–1 residue-C). However, initial residue quality parameters were not significantly (P > 0.05) correlated with N release from the residues. Grinding and incorporating of the residues caused a much greater immobilisation of N than when residues were cut and surface applied. When ground residues were incorporated, immobilisation of N was more severe and endured for longer in the finer textured red earth than in the coarse textured grey sand. Where residues were surface applied, N dynamics were similar for both soil types. The results of this study suggest that legumes used as a mulch in eucalypt plantations are a readily available source of N for trees, and that the benefits from retention of harvest residues are more likely in maintaining soil N fertility on the long-term.     

Kinetic parameters of nitrogen mineralization rates of leguminous crops incorporated into soil

Summary Fresh leguminous plant residues were incorporated into soil columns and incubated at 23°C for up to 20 weeks. The N released from specific fractions (foliage, stems, and roots) of each residue were monitored at specific time intervals. Relationships between organic carbon, total nitrogen, CN ratio, lipids, and lignin content of the plant materials and the cumulative amount of N mineralized in soil were investigated. Statistical analyses indicated that the rates of N mineralized were not significantly correlated with the organic C nor lipid content of the residues. However, the cumulative amount of N released was significantly correlated with the total N content of the plant material (r=0.93^***). The percentage of organic N of the legumes mineralized in soil ranged from 15.9 to 76.0%. The relationship between the percentage of N released and the CN ratio of the plant material showed an inverse cuvilinear response (r= 0.88^***). It was also evident that the composition of lignin in the residue influenced N mine-ralization rates of the leguminous organs incorporated into soil.There was a curvilinear relationship between the cumulative amount of N released from the residues and time of incubation. Nitrogen mineralization rates were described by first-order kinetics to estimate the N mineralization potential (N₀), mineralization rate constant (k), and the time of incubation required to mineralize one-half of N₀ (t_1/2). The kinetic parameters were calculated by both the linear least squares (LLS) and nonlinear least squares (NLLS) transformations. The N₀ values among the crop residues varied from –35 to 510 g Ng^–1 soil. Statistical analyses revealed that the N₀ values obtained by both LLS and NLLS methods were significantly correlated (r=0.93^***). The mineralization rate constants (k) of the residues ranged from 0.045 to 0.325 week^–1. The time of incubation required to mineralize one-half the nitrogen mineralization potential (t_1/2) of the legumes incorporated into soil ranged from 2.1 to 15.4 weeks.     

Biochar amendment to soils with contrasting organic matter level: effects on N mineralization and biological soil properties

Four biochar types, produced by slow pyrolysis of poultry litter (PL) and pine chips (P) at 400 or 500 °C, were added to two adjacent soils with contrasting soil organic matter (SOM) content (8.9 vs. 16.1 g C kg^?1). The N mineralization rate was determined during 14‐week incubations and assessments were made of the microbial biomass C, dehydrogenase activity, and the microbial community structure (PLFA‐extraction). The addition of PL biochars increased the net N mineralization (i.e., compared to the control treatment) in both soils, while for treatments with P biochars net N immobilization was observed in both soils. Increasing the pyrolysis temperature of both feedstock types led to a decrease in net N mineralization. The ratio of Bacterial to Fungal PLFA biomarkers also increased with addition of biochars, and particularly in the case of the 500 °C biochars. Next to feedstock type and pyrolysis temperature, SOM content clearly affected the assessed soil biological parameters, viz. net N mineralization or immobilization, MBC and dehydrogenase activity were all greater in the H soil. This might be explained by an increased chance of physical contact between the microbial community activated by SOM mineralization upon incubation and discrete biochar particles. However, when considering the H soil's double C and N content, these responses were disproportionally small, which may be partly due to the L soil's, somewhat more labile SOM. Nonetheless, increasing SOM content and microbial biomass and activity generally appears to result in greater mineralization of biochar. Additionally, higher N mineralization after PL addition to the H soil with lower pH than the L soil can be due to the liming effect of the PL biochars.     

Shifts in priming partly explain impacts of long‐term nitrogen input in different chemical forms on soil organic carbon storage

Input of labile organic carbon can enhance decomposition of extant soil organic carbon (SOC) through priming. We hypothesized that long‐term nitrogen (N) input in different chemical forms alters SOC pools by altering priming effects associated with N‐mediated changes in plants and soil microbes. The hypothesis was tested by integrating field experimental data of plants, soil microbes and two incubation experiments with soils that had experienced 10 years of N enrichment with three chemical forms (ammonium, nitrate and both ammonium and nitrate) in an alpine meadow on the Tibetan Plateau. Incubations with glucose–¹³C addition at three rates were used to quantify effects of exogenous organic carbon input on the priming of SOC. Incubations with microbial inocula extracted from soils that had experienced different long‐term N treatments were conducted to detect effects of N‐mediated changes in soil microbes on priming effects. We found strong evidence and a mechanistic explanation for alteration of SOC pools following 10 years of N enrichment with different chemical forms. We detected significant negative priming effects both in soils collected from ammonium‐addition plots and in sterilized soils inoculated with soil microbes extracted from ammonium‐addition plots. In contrast, significant positive priming effects were found both in soils collected from nitrate‐addition plots and in sterilized soils inoculated with soil microbes extracted from nitrate‐addition plots. Meanwhile, the abundance and richness of graminoids were higher and the abundance of soil microbes was lower in ammonium‐addition than in nitrate‐addition plots. Our findings provide evidence that shifts toward higher graminoid abundance and changes in soil microbial abundance mediated by N chemical forms are key drivers for priming effects and SOC pool changes, thereby linking human interference with the N cycle to climate change.     

14C tebuconazole degradation in Colombian soils

Tebuconazole is a fungicide used on onion crops (Allium Fistulosum L) in Colombia. Persistence of pesticides in soils is characterized by the half-life (DT50), which is influenced by their chemical structure, the physical and chemical properties of the soil and the previous soil history. Based on its structural and chemical properties, tebuconazole should be expected to be relatively persistent in soils. Laboratory incubation studies were conducted to evaluate persistence and bond residues of 14C tebuconazole in three soils, two inceptisol (I) and one histosol (H). Textural classifications were: loam (101), loamy sand (102) and loam (H03), respectively. Data obtained followed a first-order degradation kinetics (R2 > or = 0.899) with DT50 values between 158 and 198 days. The production of 14CO2 from the 14C-ring-labelled test chemicals was very low and increased slightly during 63 days in all cases. The methanol extractable 14C-residues were higher than aqueous ones and both decreased over incubation time for the three soils. The formation of bound 14C-residues increased with time and final values were 11.3; 5.55 and 7.87% for 101, 102 and H03 respectively. Soil 101 showed the lowest mineralization rate and the highest bound residues formation, which might be explained by the clay fraction content. In contrast, an inverse behavior was found for soils 102 and H03, these results might be explained by the higher soil organic carbon content.     

Microbial activity in pig slurry-amended soils under aerobic incubation

A 120-day aerobic incubation experiment was conducted to study the effects of pig slurry application on soil microbial activity. Pig slurry was added to soil at rates of 0 (control treatment), 150 and 300 m³ ha⁻¹. Soil samples were taken after 0, 7, 14, 30, 45, 60, and 120 days of incubation and analyzed for total organic C and microbial biomass C contents, and basal respiration. Most of the organic C applied to soil with pig slurry was readily decomposed within 30 days. During the first phase (0 to 14–30 days), the addition of pig slurry to the soil, especially at the larger rate, increased microbial biomass C content, microbial biomass C/total organic C ratio, basal respiration, and metabolic quotient. The microbial growth and the increase of their activity that these results reflected were not persistent, since the initially measured values in pig slurry-amended soils decreased and reached those of the control soil in a relatively short time.     

Visible near-infrared reflectance spectroscopy as a predictive indicator of soil properties

It is becoming increasingly important to improve spatial resolutions of soil maps as a fundamental information layer for studying ecological processes and to tackle land degradation. There is growing interest in the use of remote sensing technologies to assist the identification and delineation of spatial variation in soils. This paper investigates whether selected properties of extensively weathered, low fertility soils can be predicted using high-resolution reflectance spectra over the range 400–2500 nm. Clay content, carbonate concentration, organic carbon content and iron oxide content were analysed for 300 soil samples collected from the Jamestown, Belalie district, South Australia. The paper also examines the efficacy of this soil analysis methodology to supplement or replace traditional soil sampling in soil survey to increase sampling density and improve the spatial resolution of soil maps.Reflectance spectra were obtained from air-dried samples under controlled laboratory conditions using an ASD FieldSpec Pro spectroradiometer. Partial least squares regression was used to examine relationships between soil mineralogy, clay content and organic carbon and the reflectance spectra and identify the wavelengths contributing to prediction of these soil properties. Results show that it is possible to predict clay content, soil organic carbon, iron oxide content and carbonate content. Cross-validation R² values for all analyses were above 0.5 and the residual prediction difference (RPD) was acceptable for all soil properties. Carbonate and clay content were more accurately predicted than iron oxide and organic carbon. All samples were collected from the same geographical area such that they represented physical properties over a naturally occurring range and provide a prediction that could be related to subsequent image analysis or be used to carry out local scale soil survey. A rapid and reliable form of soil mapping could be developed from this methodology.