摘要:

A chemical fractionation scheme for boron (B) developed previously for minerals and synthetic soils was used on twenty‐four soils with a wide range of physical‐chemical properties. The scheme differentiated soil B as readily soluble (0.01M CaCl2), specifically adsorbed (0.05M KH2PO4), oxide bound (0.20M acidic NH4‐oxalate), organically bound (0.02M HNO3+ 30% H2O2), and residual (HNO3+ HCl + HF). On the average, the readily soluble and specifically adsorbed B fractions accounted for less than 2% of the total soil B in a sequential extraction procedure. Mean contents of extractable B were 2.3% associated with various oxides and oxyhydroxides, and 8.6% in organically bound forms. The major portion of soil B existed in residual or occluded forms. The procedure was found to be satisfactory in terms of sensitivity and precision for the fractionation of B. A highly linear correlation coefficient of 0.972 was found between the sum of the five B fractions and total soil B content. Readily soluble B was positively correlated with both pH and cation exchange capacity (CEC), while negatively correlated with contents of DCB‐extractable aluminum (Al). Specifically adsorbed B was only correlated with the DCB‐extractable iron (Fe) content. Organically bound B was correlated with the contents of both clay and organic carbon (C). The general agreement between the separate and sequential extraction procedures suggested that the fractionation scheme was reasonably feasible.

ISSN:0010-3624    

DOI:10.1080/00103629409369157

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Near Infrared Spectroscopy (NIRS) has been successful in the determination of protein in forages and grains. Therefore, its expansion into the determination of nitrogen (N) and starch in cotton leaves was explored. Calibration of NIRS spectra of cotton leaves with standard laboratory procedures produced equations that were utilized, not only on same season leaf samples (1991) but also on leaf samples collected over a three‐year period (1990–1992). Samples from each of the collection years should improve equation bias and coefficient of determination.

ISSN:0010-3624    

DOI:10.1080/00103629409369158

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In the apple orchard, trees fertilized with calcium nitrate resulted in the highest soil pH (6.4) whereas the lowest pH (4.7 and 4.6) occurred with ammonium nitrate and with mono‐ammonium phosphate (MAP) applications, respectively. Soil pH values were lowest with the high rates of nitrogen (N) fertilizers. Red skin color of ‘Delicious’ apples was generally improved with calcium nitrate fertilization, higher soil pH values, and with lower fruit manganese (Mn) concentrations or with lower N fertilizer rates. Incidence of bitter pit was lowest for trees fertilized with ammonium nitrate or calcium nitrate. In the pear orchard, the lowest soil pH (4.2) occurred when trees were fertilized with the high rate of MAP and the highest soil pH (4.8) occurred with the high rate of calcium nitrate applications. Fruit size was slightly smaller on trees fertilized with the high rate of MAP. Lowest incidence of superficial cork or green stain fruit disorders occurred on trees receiving the high rate of calcium nitrate. Fruit quality and mineral nutrient composition of leaves and fruit were determined for apples and pears.

ISSN:0010-3624    

DOI:10.1080/00103629409369159

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Laboratory and greenhouse experiments were conducted to study the relationships among phosphate (P) fractions, P soil tests, and P bioavailability of tropical soils. In both studies, soil samples were equilibrated with two levels of CaCO3and three of P during two incubation periods. A sequential fractionation procedure was followed to extract inorganic P fractions (Pi) resin‐P, Bic‐P, NaOH‐P I and II, HCl‐P, H2SO4‐H2O2‐P. Dry matter and P uptake by maize(Zea maysL.) were evaluated in the greenhouse experiment. Results indicated that amounts of Pi varied widely according to levels of lime, P, and incubation time. Resin‐P and Bic‐P, the most abundant Pi, were highly correlated with dry matter weight and plant uptake of P regardless of incubation interval. Highly significant correlations (P < 0.01) were found for Bray P‐1 versus resin‐P and Bic‐P, Olsen‐P versus most P fractions, and Mehlich I‐P versus resin P, Bic‐P, and residual‐P, probably because of the ability of most of these chemical extractants in identifying selectively P fractions. Relationships between plant growth parameters and soil tests were also examined.

ISSN:0010-3624    

DOI:10.1080/00103629409369160

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629409369106

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor