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1.
Abstract

A greenhouse experiment was conducted with alfalfa (Medicago sativa L. cv. Aragon wide leaf) to test the performance of a zeolite (phillipsite) phosphorus‐potassium (P‐K) fertilizer versus soluble potassium dihydrogen phosphate (KH2PO4) applied to a coarse‐textured substratum consisting of a mixture 1: 4 (in volume) soihbasaltic ash. Plants were sown at four fertilization rates and five harvests were collected after nine months. The nutrient content in plant tissue was higher in the plants treated with zeolitic fertilizer, although the response was primarily due to P. No differences due to the fertilizer source were observed for dry matter yield. When considering nutrient uptake, differences between the two fertilizers were enhanced, although the results for P are more pronounced. The soil nutrient content found after the experiment shows that available P was significantly higher in those pots that received the zeolite fertilizer, but no differences were found for K.  相似文献   

2.
Abstract

The determination of soil organic matter by wet digestion techniques is a slow and laborious analysis. Loss‐on‐ignition (LOI) provides a simple alternative technique for the estimation of soil organic carbon in non‐calcareous A horizon soils of the Natal midlands and Zululand forestry regions. Using multiple regressional techniques, the relationships between loss‐on‐ignition, Walkley organic carbon and soil texture for 55 soils were determined over a range of ignition temperatures. The relationships hold best for soil samples with relatively low organic carbon contents (< 5%). The optimum temperature for ignition was found to occur at 450°C and resulted in the relationship: Soil organic carbon = 0.284*LOI percent. No advantage is gained through ignition at higher temperatures due to the loss of clay mineral structural water, even if the soil texture is accurately known.  相似文献   

3.
Abstract

This paper reviews the published methods of nitrate‐nitrogen (NO3‐N) determination with the objective to assess their applicability to soil and plant tissue anarysis. The methods are separated into three categories on the basis of the analytical approach utilized for NO3‐N determination. Strengths and weaknesses of the methods are discussed. The first analytical approach utilitizes direct measurement of NO3‐N by the following methods: (a) colorimetric (after a color producing reaction with NO3‐N), (b) potentiometric, (c) absorption of UV radiation by NO3‐N in a complex matrix, (d) transnitration of salicylic acid, and (e) chromatographic (separation and measurement of NO3‐N) methods. The second approach is based on the reduction of NO3‐N to nitrite‐nitrogen (NO2‐N), ammonium‐nitrogen (NH4‐N), or nitric oxide and measurement of the reduction product. When NO3‐N is reduced to NO2‐N, the measurement may be achieved by (a) colorimetric, (b) fluorimetric, (c) coulometric, and (d) catalytic kinetic methods. When NO3‐N is reduced to NH4‐N, the measurement is done by (a) colorimetric (after a color producing reaction with NH4), (b) potentiometric, (c) steam distillation, and (d) gas diffussion conductimetric methods. A chemiluminescence detection method is utilized when NO3‐N is reduced to nitric oxide. The third approach determines NO3‐N concentration by measuring the change in the concentration of the chemical species that react with NO3‐N and form a complex.  相似文献   

4.
Abstract

The pattern of carbon (C) storage in soils has implications for agriculture and the environment. Dynamics of organic C, in the 0‐ to 20‐cm soil depth along a toposequence in a peri urban site in Sierra Leone, West Africa, were studied. Organic C was determined by the dry‐combustion method on the following aggregate size fractions: whole soil (<2000 µm), 250–2000 µm, 53–250 µm, and <53 µm.

Mean organic C content of whole soil ranged from 4.8% on the backslope to 9.3% on the toeslope. Organic C content of aggregate size fractions increased with decreasing aggregate size. The amount of soil and organic C present in aggregate size fractions, at all positions on the toposequence, decreased with decreasing aggregate size. In general, convex upper slopes had lower contents and amounts of organic C compared to lower concave areas. This study provided benchmark levels and patterns against which changes resulting from imminent urbanization can be measured.  相似文献   

5.
Abstract

A simple and rapid procedure for the determination of organic matter content in mineral soils by loss‐on‐ignition without pretreatment was studied. Attention was given to the possible effect of inorganic compounds abundant in mineral soils on the estimation of organic matter content by this method. Both fast heating (DTA‐TGA type) studies and prolonged heating procedures were employed on natural and “synthetic”; soils. The results were compared to those obtained by the dichromate wet‐oxidation method widely used in soil laboratories for organic matter determination. In a group of 91 soils collected from various mineral soils in Israel, and having OM contents between 0.09 and 13.23%, a correlation coefficient of 0.972 was obtained for the linear regression between organic matter content measured by the proposed method and organic carbon measured by the dichromate wet‐oxidation method.  相似文献   

6.
Abstract

A method is proposed for determination of hot‐water‐soluble boron in acid soils from western Oregon. The soil sample is boiled in 0.02 M CaCl2, filtered, and B determined using azomethine‐H. Soils extracted in this way yielded extracts with little color in them and the predicted error due to this color was 0.00–0.07 ppm B. The use of charcoal as a decolorizing agent resulted in comparatively high predicted errors.

Inductively‐coupled plasma emission spectroscopic (ICP) analysis of distilled water and 0.02 M CaCl2 extracts indicated that the extractable B level was not affected by the presence of CaCl2. Azomethine‐H yielded comparable values to ICP but the curcumin method tended to give high values for hot‐water‐soluble B.  相似文献   

7.
No‐till (NT) system with crop rotation is one of the most effective strategies to improve agricultural sustainability in tropical and subtropical regions. To control soil acidity in NT, lime is broadcast on the surface without incorporation. The increase in soil pH due to surface liming may decrease zinc (Zn) availability and its uptake by crops. A field experiment was performed in Paraná State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate Zn bioavailability in a NT system after surface liming and re‐liming. Dolomitic lime was surface applied on the main plots in July 1993 at the rates of 0, 2, 4, and 6 Mg ha?1. In June 2000, the main plots were divided in two subplots to study of the effect of surface re‐liming at the rates of 0 and 3 Mg ha?1. The cropping sequence was soybean [Glycine max (L.) Merrill] (2001–2 and 2002–3), wheat (Triticum aestivum L.) (2003), soybean (2003–4), corn (Zea mays L.) (2004–5), and soybean (2005–6). Soil samples were collected at the following depths: 0–0.05, 0.05–0.10, and 0.10–0.20 m, 10 years after surface liming and 3 years after surface re‐liming. Soil Zn levels were extracted by four extractants: (i) 0.005 mol L?1 diethylenetriaminepentaacetic acid (DTPA) + 0.1 mol L?1 triethanolamine (TEA) + 0.01 mol L?1 calcium chloride (CaCl2) solution at pH 7.3 (DTPA–TEA), (ii) 0.1 mol L?1 hydrochloric acid (HCl) solution, (iii) Mehlich 1 solution, and (iv) Mehlich 3 solution. Zinc concentrations in leaves and grains of soybean, wheat, and corn were also determined. Soil pH (0.01 mol L?1 CaCl2 suspension) varied from 4.4 to 6.1, at the 0‐ to 0.05‐m depth, from 4.2 to 5.3 at the 0.05‐ to 0.10‐m depth, and from 4.2 to 4.8 at the 0.10‐ to 0.20‐m depth, after liming and re‐liming. Zinc concentrations evaluated by DTPA–TEA, 0.1 mol L?1 HCl, Mehlich 1, and Mehlich 3 solutions were not changed as a result of lime rate application. Re‐liming increased Zn concentrations extracted by 0.1 mol L?1 HCl at 0–0.05 m deep and by DTPA–TEA at 0.05–0.10 m deep. Surface‐applied lime promoted a decrease in Zn concentrations of the crops, mainly in grains, because of increased soil pH at the surface layers. Regardless of the liming treatments, levels of Zn were sufficient to soybean, wheat, and corn nutrition under NT.  相似文献   

8.
Co‐application of biosolids and water treatment residuals (WTR) land has not been extensively studied but may be beneficial by sorbing excess biosolid‐borne or soil phosphorus (P) onto WTR, reducing the likelihood of off‐site movement. Reduction of excess soil P may affect the role of specific P‐cleaving enzymes. The research objective was to understand the long‐term effects of single co‐applications and the short‐term impacts of repeated co‐applications on soil acid phosphomonoesterase, phosphodiesterase, pyrophosphatase, and phytase enzyme activities. Test plots were 7.5 × 15 m with treatments consisting of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha?1; 10 Mg biosolids ha?1) surface co‐applied once in 1991 or reapplied in 2002. Control plots consisted of those that received no WTR–biosolids co‐applications and plots that received only 10 Mg biosolids ha?1. Plots were sampled to a 5‐cm depth in 2003 and 2004, and soil phosphatases and phytase enzyme activities were measured. Soil phosphodiesterase activity decreased in WTR‐amended plots, and pyrophosphatase activity decreased with increasing WTR application rates. In contrast, acid phosphatase and phytase activity increased with WTR addition, with WTR application possibly triggering a deficiency response causing microorganisms or plants to secrete these enzymes. Biosolids and WTR co‐applications may affect enzymatic strategies for P mineralization in this study site. Reductions in phosphodiesterase activity suggest less P mineralization from biomass sources, including nucleic acids and phospholipids. Increased acid phosphatase and phytase activities indicate that ester‐P and inositol‐P may be important plant‐available P sources in soils amended with WTR.  相似文献   

9.
The objective of this study was to establish whether the iron‐stress responses observed in T203 soybean (Fe‐inefficient) with active nodules are products of the nodules or of the entire root system. A split‐root system was used in which half the roots of each plant were inoculated and actively fixing nitrogen and the other half were not. Soybean cultivar T203 is normally Fe‐inefficient and does not exhibit the Fe‐stress responses, however an iron‐stress response did occur during active N2 fixation in earlier studies. This implies that the active nodules influenced the plant's ability to respond to Fe‐deficiency stress. In this study, the Fe‐stress response (H+ and reductant release) observed in T203 soybean was limited to the inoculated side of the split‐root system. The severe Fe chlorosis which developed in these plants was overcome in a manner similar to Fe‐efficient cultivars undergoing normal Fe‐stress response and the T203 plants completely regreened. Exudation of H+ ions was similar in both the presence and absence of Fe, and was generally limited to inoculated roots. Reductant release was nearly nonexistent from the non‐inoculated roots and was greater for the Fe‐stressed (‐Fe) plants than for non‐stressed (+Fe) plants. Thus, the response observed, which alleviated Fe chlorosis, appeared to be associated with N2 fixation of the active nodules.  相似文献   

10.
Abstract

Overwintering soil temperature may influence crop response to phosphorus (P) and indices of P availability in the humid, temperate, transitional climate of Tennessee. The effects of P fertilization and soil incubation temperature on sorghumsudangrass (Sorghum bicolor x S. Sudanese) grown on a Typic Hapludalf was investigated in a greenhouse study. In order to determine the effect of temperature on P availability, soils were incubated prior to cropping, at a constant temperature of 6°C or an average diurnal temperature of 24 and 36°C. Reagent grade Ca(H2PO4)2.H2O was used as the fertilizer source and applied at rates of 0, 10, 20, and 30 mg P kg‐1 for the first test and 0, 20, 40, 60, and 80 mg P kg‐ 1 for the second test. Critical P concentration in the shoots for optimum yield was found to be 1.3 mg g‐1, corresponding to soil solution and labile P concentrations of 5.5 μmol L‐1 and 167 μg g‐1, respectively. Optimum yield occurred for applications of >65 mg P kg‐1 and was unaffected by soil incubation temperature. Applied P rates affected extractable P by five chemical extractants (Bray I, Bray II, Mehlich I, Mehlich III, and Mississippi), but soil incubation temperature had no affect. The extractants, however, were poorly correlated to plant P uptake and no one extractant appeared preferable to the others as an indicator of P availability.  相似文献   

11.
The effects on two‐week‐old plants of a salt‐tolerant line (Euroflor) and a salt‐sensitive (SMH‐24) line of sunflower, of varying sodium/calcium (Na/ Ca) ratios in a saline growth medium were assessed after three weeks growth in sand culture under greenhouse conditions. The different Na/Ca ratios of the salt treatment were 36.5, 74.0, and 149, at a constant concentration of 150 mol m‐3 NaCl. Euroflor was superior to SMH‐24 in fresh and dry matters of shoots and roots at varying external Na/Ca ratios. The leaf Na+ concentration in SMH‐24 increased consistently with increase in external Na/Ca ratio, whereas that in Euroflor remained almost unaffected. Although leaf chlorine (Cl‐) was significantly greater in SMH‐24 than Euroflor, there was no effect of decreasing Ca2+ concentration of the saline growth medium on the leaf Cl‐ concentrations of both lines. The lines did not differ in K+, Ca2+ or Mg2+ concentrations of both shoots and roots. The leaf K/Na and Ca/ Na ratios, K versus Na selectivity were considerably higher in Euroflor than in SMH‐24. The lines also did not differ in leaf water potential and gas exchange and these variables were not affected due to decreasing Ca2+ concentration of the saline growth medium. Stomatal conductance and transpiration remained unchanged in Euroflor, whereas those in SMH‐24 decreased significantly at the highest external Na/Ca ratio. Euroflor had significantly greater stomatal conductance and transpiration than those of SMH‐24 at almost all external Na/Ca ratios, whereas the reverse was true for water use efficiency. It was established that Euroflor was tolerant to low Ca2+ concentrations of the saline growth medium as compared with SMH‐24. This was mainly attributable to accumulation of relatively low Na+ and Cl‐ in the leaves, and maintenance of high leaf K/Na and Ca/Na ratios and K versus Na selectivity in Euroflor.  相似文献   

12.
Abstract

Cation‐exchange capacity (CEC) of 30 Alabama soils was estimated by two different methods based or routine soil‐test results consisting of soil‐water pH, Adams‐Evans buffer pH, and Mehlich‐1 extractable cations (K, Mg, and Ca), which were obtained automatically by a computerized data acquisition system. In one method, CEC was calculated by solving a quadratic equation involving soil‐water and buffer pH's; in the other, CEC was estimated as the summation of extractable cations and exchangeable acidity. The two estimated CEC's agreed well with each other and also had the same magnitude as CEC determined by the normal NaOAc, pH 8.2 method. By averaging the two calculated values, an even closer estimation of the measured CEC was found. These calculations and comparisons can be accomplished quickly and efficiently by a minicomputer via a simple FORTRAN program.

In addition, a discrepancy between the two estimated CEC's would indicate possible errors in analytical determinations and/or the inadequacy of the soil testing procedures. Therefore, an additional means for quality control in a routine soil‐test operation can be obtained by comparing the two CEC values.  相似文献   

13.
《Journal of plant nutrition》2013,36(7):1467-1482
Abstract

Plant part analysis for evaluating the nutritional state of the crops is a practice commonly used. The analysis of flowers can allow an earlier diagnosis of nutritional deficiencies, excesses or unbalances, which facilitates its correction before the occurrence of irreversible losses in productivity and quality. The objective of this study were to determine the coffee tree (Coffea arabica L.) flower nutrients sufficiency ranges, to compare and correlate concentrations of nutrients observed in flowers and leaves collected 90 days after bloom, and to correlate the concentrations of nutrients in flowers and leaves with fruit yield. Samples of 26 experimental plots were collected. The plots were set up in nine different orchards five to nine years old and with 3000–5000 plants/ha, in the region of Viçosa, Minas Gerais State, Brazil. Eleven experimental plots were selected with mean yield greater than 7.0 kg/plant of coffee berry for the calculation of the nutrients sufficiency ranges. The concentrations of nitrogen (N), potassium (K), boron (B), iron (Fe), and zinc (Zn) were similar in flowers and leaves, whereas those of phosphorus (P), calcium (Ca), magnesium (Mg), sulfur (S), copper (Cu), and manganese (Mn) differed among the parts. There was correlation among the contents of N, Mg, Fe, Mn, Zn, and Cu in flowers and in leaves. For flowers a model of six variables and for leaves a model of eight variables explained 80% of the variation in the mean yield of the coffee tree plants. It is concluded that, flowers permit earlier diagnosis and greater precision in the diagnosis of the nutritional state of the coffee tree.  相似文献   

14.
Soil sampling is an integral component of fertility evaluation and nutrient recommendation for efficient use of nutrients in crop production. Little attention has been devoted to evaluating methodology for sampling watersheds under dryland agriculture. A stratified random sampling methodology for sampling the Appayapally watershed in Mahabubnagar district of Andhra Pradesh state in the semi‐arid tropical region of India was adopted and evaluated. The watershed has an area of about 500 ha, with gentle sloping lands (<1% slope), and 217 farmers own land in the watershed. The soils are Alfisols. A total of 114 soil samples were collected from the top 15‐cm layer to represent the entire watershed. Each sample was a composite of 7–8 cores, randomly collected from the area represented by a crop and group of farmers. The soil samples were air dried, ground, and analyzed for pH, electrical conductivity (EC), organic carbon (C), total nitrogen (N), and extractable phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), sulfur (S), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), and boron (B). Statistical analysis of the results on soil fertility parameters showed that the mean‐ or median‐based results of soil tests performed in the study did not differ significantly when the sample set size varied from 5 to 114 (100% of the population). Our results indicate that farmers' fields in the Appayapally watershed are uniform in the chemical fertility parameters studied, and even a small sample set size can represent the whole population. However, such a sampling strategy may be applicable only to watersheds that are very gently sloping and where fertilizer use is very low, resulting in an overall low fertility in the whole watershed.  相似文献   

15.
In a ten‐year study of potassium (K) and lime application to a Kalmia sandy loam (fine‐loamy, siliceous, thermic Typic Hapludult), a soil high in nonexchangeable K, corn (Zea mays L.) and soybean [Glycine max (L.) Herr.] have not responded to applied K. The objectives of this study were to determine if a high K‐requiring crop such as tomato (Lycocersicon esculentum Mill. cv. Redpak) would respond to KCl fertilizer rate or lime type (dolomitic, calcitic, and mixed) and rate on such a soil. Potassium was applied at 0, 56, and 112 kg K/ha every year for ten years. Lime was applied at 0, 2, and 9 Mg/ha in calcitic, mixed, and dolomitic forms twice in ten years (1970 and 1973). In 1980, the tenth year of the study, tomato fruit was harvested by hand once‐over to simulate machine harvest and divided into four maturity groups by color. Soil pH was higher with dolomitic than calcitic lime. Soil K saturation was not influenced by lime rate or type. Fruit yield and leaf phosphorus (P), calcium (Ca), and magnesium (Mg) concentrations increased with increasing lime rates. Leaf K, manganese (Mn), iron (Fe), boron (B), copper (Cu), zinc (Zn), barium (Ba), strontium (Sr), and aluminum (Al) concentrations decreased with increasing lime rate. Leaf Mn, Ba, and Sr concentrations were lower with dolomitic than with calcitic lime. Lime type had no effect on tomato yield. Wide ranges in basic cation saturation ratios had little effect on yield. Soil K saturation and leaf K, Zn, and Ba concentrations increased with increasing K rate. Soil Ca and leaf Ca, Mg, and Al concentrations decreased with increasing K rate. Applied K had no effect on total yield but onceover marketable yield increased linearly with increasing K rate. Marketable yield increased 14% with an increase in K rate from 0 to 56 kg/ha. Thus, fruit maturity was apparently hastened by K fertilization.  相似文献   

16.
Abstract

Buffers for determining a soil's lime requirement (LR) sometimes contain hazardous chemicals. Our objective was to implement a single‐addition titration with calcium hydroxide [Ca(OH)2] to determine the LR of soils. The soil pH buffering capacity is calculated from the rise in pH from a single addition of base. The LR is calculated from the soil pH buffering capacity, the target pH, and initial soil pH. The LR of 531 randomly selected client samples determined by single‐addition titration were slightly higher than by the Adams–Evans (AE) buffer procedure when LRs were less than 1800 lb per acre. The new procedure recommended about 11% less lime than AE at LRs greater than 1800 lb per acre. Independent evaluations of samples that gave the most widely different LR revealed that the single‐addition titration was more accurate and more precise than the AE buffer.  相似文献   

17.
Abstract

Changing conventional tillage to conservation tillage systems affects nitrogen (N) cycling in agroecosystems. Our objective was to evaluate the role of soil organic pools, specially plant residues, as sources‐sinks of nitrogen in an humid and warm temperate environment cropped to wheat, under plow‐ and no‐tillage. The experimental site was in the Argentine Pampa on a Typic Hapludoll. A balance‐sheet method was used: Nupt+Nres=Nsow+Nmin, where Nupt=N uptake by the crop at harvest; Nsow=soil mineral N as NH4 and NO3 at 0–90 cm depth, one month before sowing, plus N added as fertilizer; Nres=residual soil mineral N as NH4 and NO3 at 0–90 cm depth, at harvest; Nmin=N mineralized from humus and plant residues during wheat growing period. Nupt did not differ between tillage systems. Nitrogen supply by the mineral N pool, estimated by the difference Nsow‐Nres, was ca. 150 kg N ha‐1 in both tillage systems. Plant residues decomposed and released N under both treatments. This organic N pool decreased 77% along the crop cycle. Nmin, calculated using the balance equation was 83 kg N ha‐1, and did not differ between tillage managements, representing 35% of Nupt. This results highlight the importance of the organic pools as sources of N for wheat in the Humid Pampa. They also brink our attention on the importance for evaluate residue decomposition and humus mineralization in warm‐temperate regions when fertilizer requirements are determined, in order to minimize environmental hazard and economic losses by overfertilization.  相似文献   

18.
Abstract

Development of a nitrate quick‐test for use by fanners or field consultants would likely encourage the use of plant tissue and soil nitrate tests as a means to improve nitrogen management. To evaluate a quick‐test method, nitrate concentrations in plant tissue and soils were measured using commercially available nitrate test strips and a hand‐held reflectometer. The results were compared with those obtained with standard laboratory methods. Test strip accuracy and precision and reflectometer precision were determined over a 10 day period using standard KNO3solutions and colored paper strips. Coefficients of variation ranged from 22.4 to 9.5 percent for the test strips and from 3.5 to 1.6 percent for the reflectometer. Quick‐test results were highly correlated with laboratory results for both plant tissue nitrate (r=0.87) and soil nitrate (r=0.98) concentrations. Results indicated that test strips provide a rapid, reasonably accurate and precise method to determine nitrate concentrations in both soil and plant material  相似文献   

19.
Abstract

Conventional methods for labeling of legume residues with 15N for the measurement of the transfer of nitrogen (N) to a succeeding crop are inadequate for zero‐tillage management where the residue is chemically desiccated. The study tests the feasibility of in situ labeling of legumes with 15N for the study of N transfer to a succeeding crop. A single foliar application of 15N‐labeled urea was misted onto the stems and leaves of second cut red clover and alfalfa in the field in 0.75 x 0.75 m microplots. Nitrogen content and 15N enrichment were determined for above‐ and below‐ground plant parts. Overall, recovery of the foliar applied 15N in the forage was 30% and 57% for the alfalfa and red clover, respectively. Of the nitrogen recovered, approximately 70% and 30% were recovered in the above‐ and below‐ground plant parts, respectively, for both forage species. Atom % 15N was similar for the red clover and alfalfa for each of the above‐ground plant parts and was slightly lower in the crown and roots for the red clover than for the alfalfa. Values of atom % 15N ranged from 0.5 for fine roots to 1.5 for leaves above 0.20 m from the ground. Labeling of the plant material was not uniform between plant parts but was adequate for many studies of N transfer to a succeeding crop.  相似文献   

20.
Abstract

Chemical fractions of copper (Cu) and zinc (Zn) in the organic‐rich particles collected from filtered aqueous extracts (<20 μm) of an acid soil were determined. A sequential extraction procedure was used to partition the particulate Cu and Zn into four operationally defined chemical fractions: adsorbed (ADS), iron (Fe) and manganese (Mn) oxides bound (FeMnOX), organic matter bound (OM) and residual (RESD). Total extractable concentrations of Cu and Zn in the fine particles were higher than their total concentrations in the original bulk soil. The concentration of particulate Cu was usually much higher than that of particulate Zn. Addition of lime stabilized sewage sludge cake and/or inorganic metal salts markedly increased the concentrations of particulate Cu and Zn in aqueous extracts, especially from limed soil. The proportional distributions of particulate Cu and Zn were quite similar. The two particulate metals were present predominantly in the ADS and FeMnOX fractions, with less (about 20%) in the OM and RESD fractions. Some of the ADS metal fraction was associated with dissolved organic substances. The concentrations of particulate Cu and Zn in the various extractable fractions were significantly affected by the application of lime, lime stabilized sewage sludge cake, or inorganic metal salts.  相似文献   

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