摘要:

A soil test for nitrogen availabilty to corn(Zea mays,L) has gained wide acceptance in the northeast region of the United States. The test involves sampling the surface 30 cm of soil during the early part of the growing season. The N03‐N present at that time is correlated with the probability of obtaining a yield increase by using sidedress nitrogen fertilizer. The test has been evaluated in 272 yr‐site N response experiments in Vermont, Pennsylvania, Connecticut, New York, and New Hampshire. The various states in the region that are now offering a N soil test (Vermont, Pennsylvania, Connecticut, and Maine) have different methods of making recommendations based on soil‐test levels. However, 20 to 30 mg NO3‐N/kg soil is about the critical range above which there is a low probability of obtaining yield increases due to sidedress fertilizer N. Therefore, no additional N fertilizer is recommended. A major problem, which is slowing widespread utilization of this test is that the soil must be sampled at a different time of the year than the routine soil tests which are usually sampled in either the fall or prior to the growing season in the spring. Other critical issues include the deeper sampling and rapid drying needed as well as the rapid turnaround time required to get the samples to the laboratory, through the laboratory, and back to the farmer. There is only a limited “window”; of time available between soil sampling and the period for timely fertilizer N sidedressing. Various states are using different innovative programs to help introduce farmers to the test and to speed total turnaround time.

ISSN:0010-3624    

DOI:10.1080/00103629009368293

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Forty factorial experiments with 4 levels of N (0, 40, 80, and 120 kg N/ha and 4 levels of P (0, 8.8, 17.5, and 35 kg P/ha) with two replicates were conducted in farmers’ fields during two consecutive seasons in 1987 and 1988. The sites chosen had different soil fertility levels and the precedent crop was either local lentil (Lens esculentium), local chickpea (Cicer arietinum), or summer crop, such as watermelon (Citrullus sp.) or sunflower (Helianthus annum).

ISSN:0010-3624    

DOI:10.1080/00103629009368294

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The Pi test is a new soil test for phosphorus (P), which uses a strip of iron oxide‐impregnated paper as a sink to adsorb P mobilized in a soil‐solution suspension. The paper strips are prepared by immersing hardened filter paper circles in a 10% solution of ferric chloride; then they are dried and exposed to ammonia vapor. The paper is then cut into strips 10 cm long and 2 cm wide. To extract P, 1 g of soil is shaken for 16 h with 40 mL 0.01MCaCl2and a Pi strip, which is enclosed in a nylon mesh bag. Phosphorus retained on the strip is dissolved in 0.1MH2SO4and measured. The amount of P extracted by the paper strips has been found to correlate well with yield and P uptake by maize(Zea MaysL., Var. Funk 5757) grown on acidic, alkaline, and calcareous soils and in soils fertilized with soluble fertilizers and phosphate rock.

ISSN:0010-3624    

DOI:10.1080/00103629009368295

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A simple accurate method of preparing soil samples for analyses of soluble and exchangeable ions is presented. A suspension is prepared from soil samples that have been taken on a volume basis and the concentration of a nutrient in the solution phase of this suspension is determined (concentration c1). An amount of water equal to the volume of soil is then added to the suspension and the concentration of the nutrient is again determined (concentration c2). The concentration of the nutrient in the soil is then c=c1c2/(c1‐c2) on a volume‐basis. Provided that it is feasible to take volume samples and that adequate quick‐tests are available, the management of fertility could be greatly improved by this method.

ISSN:0010-3624    

DOI:10.1080/00103629009368296

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Soil testing is viewed as the application of Soil Science Research. Thus, the history of soil testing is interwoven with the growth and development of soil science. Soil testing as a recognized sub‐unit of soil science emerged in the early 1940's with agriculture's transition from subsistence to production farming systems. Soil testing today enjoys popularity in direct relation to the research data base and the extent to which the crop production limiting soil factors are manageable and ameliorating materials are available at a reasonable cost.

ISSN:0010-3624    

DOI:10.1080/00103629009368297

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of two levels of K and P applications on an Italian vertisol was investigated adding known quantites of KC1 and Na2HPO4solutions, respectively. The extractions were carried out using electro‐ultrafiltration (EUF) at a constant electric field and different temperatures. The EUF data were compared with the NH4OAC extracted K and Olsen‐P values. We found that both the soluble K fraction, extracted by moderate EUF conditions, and the reserve K fraction, extracted by stronger EUF conditions, did not increase significantly with fertilization treatments. On the contrary, in the case of P the first moderate extraction assessed the different “fertilization”; levels better than the successive, more powerful procedure.

ISSN:0010-3624    

DOI:10.1080/00103629009368298

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The University of Florida's Soil Testing Laboratory for organic soils has been using a water‐extracable P soil test since 1944. This test was selected because of its reliable correlation with response of vegetable‐crop commodities produced on Histosols. However, this soil test has not consistently provided reliable correlations for agronomic crops which have a longer growing season. In the interest of calibrating an extractant for both horticultural and agronomic crops, and possibly accomplish progress toward the use of a more universal extractant for all Florida soils, data from four field experiments were used to evaluate several extractants as alternatives to the water P test currently used. Lettuce (Lactuca sativa L.) was used as the test crop and the extractants evaluated were, the sodium bicarbonate, ammonium bicarbonate‐DPTA, EDTA, Mehlich‐I, and Mehlich‐III soil test. Overall, no extractant provided superior correlations to lettuce response than the water P test. However, the M‐III extractant produced correlations that were similar to water and further evaluation of this extractant as a P soil test for Histosols is warranted.

ISSN:0010-3624    

DOI:10.1080/00103629009368299

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Cation exchange capacity (CEC) and Al saturation are often determined by extraction of the bases with 1MNH4OAc, pH 7, and the Al with 1MKCl. This method was compared to 1MNH4Cl to extract both bases and Al. The latter method has the advantages of measuring CEC at the soil pH and one‐step extraction. Data sets included three field samplings from 4 locations (7 soil types) and samples from a greenhouse experiment with 8 soils (total N=248). Differences between individual pairs of data were evaluated using T‐tests. Most soils were acid and CEC was predominated by Al and Ca. The two methods compared favorably for Al with slightly more Al being extracted by NH4Cl than by KCl. Significantly less Ca was extracted by NH4Cl than NH4OAc. Coefficients of determination were high (> 0.98) for Ca, but the regression slope was less than one (0.85). The methods compared well for extractable Mg, K, and Na, but those were minor constituents of the CEC. CEC and Al saturation differences followed those of Ca. The NH4Cl method is recommended for samples that have not been recently limed, but not for samples containing residual lime.

ISSN:0010-3624    

DOI:10.1080/00103629009368300

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Current soil tests are based on single and multiple nutrient extractions with a wide range of chemical solutions. For most nutrients this approach provides an “index”; of plant availability, but it may not be accurate on specific soils or in certain regions. Major problems with chemical extraction soil testing cannot be solved because they are inherent in the approach. The Phytoavailability Soil Test (PST) is a simplified soil‐extraction methodology based on ion‐exchange‐resin extraction of nutrients from saturated paste soil samples. The need for drying and grinding soil samples is thus eliminated. PST provides a “universal”; extraction for all nutrients. It mimics nutrient accumulation in plants, thus providing a more theoretically accurate basis for soil testing. PST also provides a system which can be “standardized”; for use in all regions. Factors which influence the rate and amount of resin‐extracted nutrients, including type of resin, shape of resin bag, soil water content, microbial activity, and temperature are presented.

ISSN:0010-3624    

DOI:10.1080/00103629009368301

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Soil‐test crop response correlation studies on postrainy season sorghum (Sept/Oct‐Dec/Jan) based on yield goal approach were conducted in a vertisol. The results indicated that 2.07 kg N, 0.34 kg P and 2.00 kg K were required to produce one quintal of grain sorghum (cv. CSH 8 R). The contribution of N, P and K from soil and fertilizers was 34, 31.87, 16.66 and 44, 17.03, 60 percent, respectively. The results of the 19 yield goal trials showed that about 75% of the yield goal of 60 q/ha were achieved within ± 10% variation. From the test of significance, the differences between the yield goal of 60 q/ha and the actual yield of sorghum obtained were nonsignificant indicating that yield goal of 60 q/ha was achieved. The results indicated higher utility of yield goal approach in making sound fertilizer recommendations for sorghum in vertisols.

ISSN:0010-3624    

DOI:10.1080/00103629009368302

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor