Application of near‐infrared spectroscopy in analysis of soil mineral nutrients

Abstract

The feasibility of using near‐infrared reflectance spectroscopy (NIRS) was investigated for the analysis of pH, electrical conductivity (EC), phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), iron (Fe), and manganese (Mn) in 28 Canadian soil samples from three boreholes down to 10 m in depth. Field moist soil samples were scanned for pH and EC, and air‐dry samples were scanned for the analysis of the elements. Calibrations were developed between the near‐infrared spectral data and results obtained by conventional analyses. The NIR‐predicted values were highly correlated to the measured values obtained by the conventional methods (r²>0.9) for P, Ca, Mg, K, Fe, and Mn, and almost as highly correlated (r²>0.8) for S and Na Results for pH were somewhat less successful (r²>0.6), and appeared to be useful only for screening purposes, whereas EC was not successfully predicted by NIRS in this study. It appeared that NIRS could be a useful method for the rapid, non‐destructive, simultaneous analysis of elemental concentrations in dry soils, useful in routine analysis.     

Are hovercraft a major cause of disturbance to intertidal invertebrates?

The densities of intertidal invertebrates in areas within and outside the hovercraft flightpath were compared by analysis of variance and least significant range tests. No evidence was found to suggest that the hovercraft had significantly reduced the density of invertebrates in the flightpath area. Only five species groups (Nereis diversicolor, Spionid spp., Bathyporeia spp., Macoma balthica and Arenicola marina) had significantly different densities between areas, and in each case there was a density gradient alongshore. In three species groups (Spionid spp., Bathyporeia spp. and Macoma balthica) density was related to the percentage of fine sand (4–5 φ) at each site.     

How Stable Are Soils for the Determination of Available N?

When potassium chloride (KCl) is used to extract “available” mineral nitrogen (N) species from field-moist soils, samples are usually transferred to the laboratory in a cool box prior to extraction and stored in a fridge until being prepared for extraction. This study shows that significant changes, especially in nitrate concentration, occur under refrigerated conditions for 16 h, especially in grassland subsoils, and these are reflected in total mineral N levels. Surprisingly, storage at room temperature for the same time caused no significant additional net nitrate production. Extractable ammonium concentrations often fell significantly during storage, especially in woodland soil samples, probably via microbial immobilization as well as nitrification. In the present study, 12 pairs of students were used to perform all extractions within 30 min of sampling in the field, which would not be generally practical. It is suggested that volumetric subsampling in the field and immediate addition to a known volume of KCl solution may be more reliable than methodology currently employed by many soil scientists.     

Magnesium fixation—a possible cause of negative yield responses to lime applications

Abstract

Negative yield responses are common when highly leached soils are limed to neutrality. A number of explanations have been proposed, but very few have been experimentally verified or are entirely acceptable. In this paper the problem is re‐examined and a new possible causal mechanism is proposed.

Data assembled from the literature are used to demonstrate that a consistently observed reduction in Mg uptake by plants when soils are limed to neutrality is often accompanied by a generally ignored reduction in exchangeable soil Mg. Using data for soils of North American and African origin, it is demonstrated that when the soils were limed with pure Ca sources, the level of exchangeable soil Mg was reduced between 36 and 93%. Furthermore, after treatment with a Mg containing liming material, initial increases in the level of exchangeable Mg were followed by similarly large decreases when the soil pH approaches neutrality.

The applicability of known Mg fixation mechanisms is briefly discussed and the suggestion is made that Mg fixation may offer an acceptable explanation for some of the yield depressions observed on liming to neutrality. Research is currently in progress to gather sufficient data to answer the many questions raised.     

Impact of organic residues and mineral fertilizer application on soil–crop systems I: yield and nutrients content

A five-season experiment was initiated to study the effects of the recycling of some organic residues on a soil–crop system of a guar–wheat rotation in a sandy clay loam soil located in the semi-arid tropics of Sudan. Treatments included: incorporation of crop residues alone after harvest (Cr⁺), with (FCr⁺) or without (FCr^?) inorganic fertilizer, sewage sludge (SS) and humentos (H). Grain yield of wheat in FCr⁺ and Cr⁺ treatments was significantly higher than that obtained in FCr^? and control plots by ～22?62% and 116?119%, respectively. When crop residues were incorporated with inorganic fertilizer, the priming effect of crop residues on straw yield (106%) was almost double that of the priming effect of inorganic fertilizer (56%). The sustainable yield index of wheat straw dry matter for the control, crop residue, humentos, inorganic fertilizer, combined fertilizer and crop residue and sewage sludge was 28, 27, 8, 35, 21 and 38%, respectively. In general, N, P and K of straw dry matter (SDM) was in the order of FCr⁺ > FCr^? > SS > Cr⁺> H > C. The findings suggest that repeated incorporation of crop residues with inorganic fertilizer and applications of SS could both sustain wheat performance in the dryland ecosystems.     

How to improve strawberry productivity,nutrients composition,and beneficial rhizosphere microflora by biofertilization and mineral fertilization?

The main objective of this study was to investigate and compare the effects of fertilizer types on the counts of soil microorganisms, the mineral leaf composition, and productivity of three strawberry cultivars in the period 2012–2013. Two types of fertilizers were applied—mineral and microbiological. Significantly higher number of Azotobacter, ammonifiers, oligonitrophils, and total microbial count were observed under biofertilizers treatment. Significantly higher counts of fungi and actinomycetes were obtained under mineral fertilizer treatment, compared to other fertilizer treatments. The use of mineral fertilizer led to the most favorable balance of macronutrients and micronutrients in the leaf. In 2012, the generative potential and yield increased after mineral fertilization, whereas in 2013 these parameters were positively affected by mineral fertilizer and Biofertilizer 1. Given the obtained results, in order to improve technology of strawberry production, a partial substitution of mineral fertilizers by microbiological ones can be recommended.     

Is overweight a risk factor for wheezing in pre-school children? A study in 14 Brazilian communities

OBJECTIVE: To evaluate the association between overweight and wheezing in pre-school children in 14 small Brazilian communities. METHODS: Cross-sectional epidemiological study, conducted between 2001 and 2002. A sample of 3453 children under 5 years of age was taken from nine communities in the state of Bahia and five in the state of S?o Paulo. Data on housing, family and children were obtained by applying structured questionnaires in loco. Weight and height for each child were also measured. The association between wheezing and overweight was assessed by unconditional logistic multivariate regression models. RESULTS: Overweight children had a greater frequency of wheezing and an odds ratio of 2.57 (95% confidence interval 1.51-4.37) was estimated after controlling for several potential confounding variables. The magnitude of the risk was not affected by several different model specifications. CONCLUSION: Excess weight is associated with increased risk for wheezing in this population of children below 5 years of age.     

Are nest boxes a viable alternative source of cavities for hollow-dependent animals? Long-term monitoring of nest box occupancy, pest use and attrition

Nest box programs have often been established to conserve hollow-dependent fauna but their effectiveness is unknown in many jurisdictions. We examined nest box effectiveness in a 10-year experimental study in the Mountain Ash (Eucalyptus regnans) forests of Victoria (south-eastern Australia) where the paucity of hollow-bearing trees is a significant conservation issue. We quantified occupancy by arboreal marsupials, infestation by pest invertebrates, and nest box attrition. We found a large proportion of nest boxes (68.8%) were never used, including by the endangered target species, Leadbeater’s Possum (Gymnobelideus leadbeateri). Nest boxes were more often occupied in younger forests (58.3% cf 4.1% for old forest) but these sites were also where infestations by the introduced European Honeybee (Apis mellifera) were greatest and where the probability of nest boxes collapsing was highest. Our data suggest that it is important to carefully target the locations where nest boxes should be established, but these same places are also those where most effort is required to maintain them, either by removing pest invertebrates and/or by re-attaching them to trees after they have fallen down.We recorded reasonable levels of occupancy by arboreal marsupials in young forest ∼2-3 years after box establishment, but then high levels of nest box attrition (>51%) occurred after 8-10 years. This suggests an “effective occupancy time” for arboreal marsupials of only ∼5 years.A key consideration must be to weigh the ecological and economic effectiveness of nest boxes against other strategies such as implementing alternative silvicultural systems that result in the creation and retention of more hollow-bearing trees within logged areas.     

Screening for phyto‐toxic contaminants in an industrial source of nutrients intended for foliar and root fertilization

Plant screening assays were used to determine whether significant levels of growth inhibitory and phytotoxic contaminants were present in a new industrial source of potassium dihydrogen phosphate fertilizer intended for foliar and root application. Maize (Zea mays L.) plants hydroponically cultured in a controlled environment chamber, were used for the assays. The threshold concentration of industrial potassium phosphate which just caused burn damage symptoms, when applied as standard droplets to the leaf surface with Tween 80 wetting agent was 0.5M. The comparative threshold concentration for damage by an ultrapure analytical grade of potassium phosphate was >0.6M. Thus, the industrial grade had slightly higher toxicity for leaf application. Effects on plants of supplying industrial and analytical grade phosphates via the roots were also compared. Root and leaf elongation kinetics, mature leaf cell lengths, apparent capacity for leaf cell production, shoot ontogeny, and shoot fresh weight yields were determined at low and high potassium phosphate concentrations. The effects of analytical and industrial grade fertilizer salts were equivalent. We suggest that these rapid and relatively simple plant screening assays can provide a useful safety check, prior to large scale field trails, for fertilizer nutrients produced by new industrial processes.     

Influence of poultry manure–derived biochars on nutrients bioavailability and chemical properties of a calcareous soil

This study was conducted to investigate the effects of poultry manure (PM) and its derived biochars on chemical properties of a calcareous soil. PM and biochars prepared at 200°C (B200), 300°C (B300) and 400°C (B400) were applied to a calcareous soil at 2% level (w/w) and incubated for 150 days. Selected soil chemical properties and phosphorous, potassium, iron, manganese, zinc and copper availability and recovery were determined at 1, 15, 45 and 150 days of incubation. Soil nutrients availability, organic carbon (OC), electrical conductivity (EC) and cation exchange capacity (CEC) increased by addition of all organic substances. Biochars prepared at higher temperatures were more effective in increasing soil OC with higher durability compared to other treatments. The addition of PM and B200 decreased soil pH, whereas B400 increased it. Although the highest soil EC was observed in B300- and B400-treated samples in the early stages of incubation, the rate of increase in soil EC was higher for PM- and B200-treated soils compared to other treatments. It was concluded that biochar prepared at 300°C had the highest positive effect on nutrients availability and lasts longer in calcareous soil compared to the other produced biochars and PM.     

Are indices reliable for assessing conservation value of natural areas? An avian case study

Bird censuses in two wetland habitats (bogs and wet meadows) in SW Sweden were used to test the applicability of five conservation indices suggested for birds. The censused sites were first evaluated and ranked by the authors, then ranked according to each of the indices. Two indices based on species diversity (H′ or Λ) showed a poor agreement with our evaluation; we suggest that they should not be used for ranking of sites of ornithological interest. Three indices based on rarity showed a better agreement with our evaluation, but were influenced by the size of the geographical area for which rarity was assessed. None of the five indices takes into account all of the relevant aspects for an evaluation of the bird fauna at the different sites. Before constructing further indices, conservationists must reach agreement on which evaluation criteria to use, and how to use them. It may, however, not be feasible to construct a single index; a better strategy might be to construct indices only for single evaluation criteria.     

Application of soil amendments to contaminated soils for heavy metal immobilization and improved soil quality—a critical review

ABSTRACT

Today, soil metal pollution has become a significant environmental issue of great public concern. This is because soil is both a major sink for heavy metal(loid)s (HMs) released into the environment, by both pedogenic and anthropogenic activities; and also a major source of food chain contamination mainly through plant uptake and animal transfer. In addition, HM contamination of soil leads to negative impacts on soil characteristics and function by disturbing both soil biological and physiochemical properties (e.g. extreme soil pH, poor soil structure and soil fertility and lack of soil microbial activity). This eventually leads to decreased crop production. Various soil remediation techniques have been successfully employed to reduce the risks associated with HMs efflux into soil. Among these, the use of low-cost and environmentally safe inorganic and organic amendments for the in-situ immobilization of HMs has become increasingly popular. Immobilization agents have successfully reduced the availability of metal ions through a variety of adsorption, complexation, precipitation, and redox reactions. Soil amendments can also be a source of nutrients and thus can also act as a soil conditioner, improving the soil’s physiochemical properties and fertility, resulting in enhanced plant establishment in metal contaminated soils. This article critically reviews the use of immobilizing agents in HM contaminated agricultural and mining soils paying particular attention to metal immobilization chemistry and the effects of soil amendments on common soil quality parameters.     

Post-fledging dispersal, habitat use, and survival of Sprague’s pipits: Are planted grasslands a good substitute for native?

Loss and degradation of native grasslands on the North American landscape are some of the key factors influencing population declines of grassland songbirds. It is unclear what role anthropogenic grasslands play in the conservation of grassland specialists and whether demographic parameters of grassland songbirds differ between anthropogenic and native grasslands. Furthermore, there has been little research examining the overlap (or lack thereof) between nesting and post-fledging habitat. We initiated a radio-telemetry study from 2004 to 2008 on dispersal, microhabitat use, and survival of juvenile Sprague’s pipits (Anthus spragueii), a threatened grassland-obligate songbird, in native pastures and fields planted with exotic species (planted grasslands). Dispersal distance was greater in planted compared to native grasslands, but appeared to be constrained to natal fields up to 26-d post-fledging. Pipits used microhabitats in planted grasslands with vegetation that was on average 11 cm taller than used locations in native pastures, possibly due to the rapid growth of planted vegetation by the time individuals fledged. Individuals that were reared in planted grasslands had consistently lower daily survival rates compared to those in native pastures. Our observation that young birds rarely left their natal field suggests that conserving nesting habitat in native pastures would be an effective management strategy for this species. However, our results suggest that planted grasslands may act as population sinks given the lower survival of juvenile pipits reared in planted fields in our region. Demographic studies during the post-fledging period are essential to determine the conservation value of anthropogenic grasslands for North American songbirds.     

Are all three components of conservation agriculture necessary for soil conservation in the Sudan Savanna?

ABSTRACT

Conservation agriculture (CA) as recommended by the Food and Agriculture Organization of the United Nations consists of three components: minimum soil disturbance, soil cover, and crop rotation/association. CA was expected to become an effective countermeasure against water erosion in the Sudan Savanna, but it has not been adopted by local smallholder farmers. As markets for grain legumes (including cowpea) have not been developed in the Sudan Savanna, crop rotation/association should be considered impractical for these farmers. Therefore, we examined whether legume intercropping as a crop rotation/association component is necessary for preventing soil erosion in the Sudan Savanna. Three-year field experiments were conducted in runoff plots at Institute of Environment and Agricultural Research Saria station. The four treatments were conventional practice (full tillage, no sorghum residue mulching, and no intercropping), two-component CA (minimum tillage (MT) and sorghum residue mulching without intercropping), and three-component CA with velvet bean (VB) or pigeon pea (PP) intercropping. It was revealed that: (1) MT and sorghum residue mulching (without intercropping) effectively reduced the annual soil loss by 54% mainly due to the improvement of soil permeability by the boring of termites and wolf spiders found under the sorghum stover mulch; (2) intercropping in combination with MT and crop residue mulching had no effect on soil erosion control mainly because: (a) PP did not survive the long dry season; (b) VB did not serve effectively as a cover crop since soil loss was concentrated at the beginning of the rainy season when VB was still too small; (c) unexpectedly, in combination with MT and crop residue mulching, intercropping with VB did not increase mulch biomass, especially sorghum biomass which prompts the boring of termites and wolf spiders. These results demonstrate that the third component of CA, namely legume intercropping, is not always necessary; rather, the two remaining components – minimum soil disturbance and soil cover – are sufficient for soil conservation in the Sudan Savanna. This finding lightens the burden of adopting CA and thus facilitates its future promotion to the smallholder farmers in the Sudan Savanna.     

Effect of wastewater irrigation on mineral com‐position of corn and sorghum plants in a pot experiment

Effect of wastewater irrigation was investigated on mineral composition of corn and sorghum plants in a pot experiment. The ranges for the concentration of different minerals in corn plants were 0.67–0.89% calcium (Ca), 0.38–0.58% magnesium (Mg), 0.09–1.29% sodium (Na), 0.81–1.87% nitrogen (N), 1.81–2.27% potassium (K), 0.12–0.16% phosphorus (P), 190–257 mg/kg iron (Fe), 3.5–5.6 mg/kg copper (Cu), 37.1–44.5 mg/kg manganese (Mn), 21.6–33.6 mg/kg zinc (Zn), 1.40–1.84 mg/kg molydbenum (Mo), 11.0–45.7 mg/kg lead (Pb), and 2.5–10.8 mg/kg nickel (Ni). Whereas for sorghum plants, the ranges were: 0.56–0.68% Ca, 0.19–0.32% Mg, 0.02–0.27% Na, 0.69–1.53% N, 1.40–1.89% K, 0.10–0.14% P, 190–320 mg/kg Fe, 3.8–6.0 mg/kg Cu, 29.2–37.6 mg/kg Mn, 21.1–29.9 mg/kg Zn, 2.2–3.7 mg/kg Mo, 12.3–59.0 mg/kg Pb, and 2.5–15.2 mg/kg Ni. Heavy metals such as cobalt (Co) and cadmium (Cd) were below detection limits at mg/kg levels. The concentrations of Ca, N, K, P, Cu, and Mn in corn plants were in the deficient range except for Mg, Fe, Zn, and Al. The concentrations of Ca, N, P, K, Cu, Mn, Mg, and Zn in sorghum plants were in the deficient range except for Fe and aluminum (Al). The analysis of regression indicated a strong interaction between Pb, Ni, Ca, and Fe in corn and sorghum plants. In conclusion, waste water irrigation did not increase mineral concentrations of either macro‐ and micro‐elements or heavy trace metals in corn and sorghum plants to hazardous limits according to the established standards and could be used safely for crop irrigation.     

Certification of an air‐dry soil for pH and extractable nutrients using one hundredth molar calcium chloride

Abstract

The preparation of an air‐dry river‐clay soil as reference soil material for pH and extractable nutrients with a 0.01 M calcium chloride (CaCl₂) solution and the homogeneity testing are described. Recommended values for pH and the concentrations of ammonium‐nitrogen (NH₄‐N), total soluble nitrogen (N), phosphorus (P), sodium (Na), potassium (K), and magnesium (Mg) using the unbuffered 0.01M CaCl₂ are given. With respect to nitrate‐nitrogen (NO₃‐N), the sample proved not to be sufficienctly homogeneous. The certified soil sample has also been used as a sample in the International Soil‐Analytical Exchange (ISE), a continuous proficiency testing scheme. The values found by the ISE laboratories compared well with the certified values.     

Reactions to soil acidification in microarthropods: Is competition a key factor?

Summary Acidification of raw humus soil in coniferous forest areas leads to characteristic changes in the microarthropod community. Certain species are calciophilic and decrease in abundance, while others are acidophilic and increase in abundance. The simplest explanation for these changes is that population levels are directly related to soil pH. This hypothesis was tested by growing small populations of selected species in monoculture at different pH levels. Three acidophilic species were tested, the collembolan Mesaphorura yosii, the oribatid mite Nothrus silvestris, and the astigmatid mite Schwiebea cf. lebruni. A slightly calciophilic collembolan, Isotomiella minor, was also included. For all species, population growth was lowest in acidified raw humus. Even acidophilic species seem to have an optimum at a high pH. It is assumed that their success in low-pH soils is due to their ability to compete under these conditions. Competition may be a key factor in microarthropod reactions to soil acidification.Dedicated to the late Prof. Dr. W. Kühnelt