摘要:

In highly weathered regions, acid, infertile subsoils limit productivity by preventing root proliferation and thereby increasing the likelihood of drought stress. An experiment on a Typic Hapludult involving surface application of gypsum and deep lime incorporation investigated the possibilities of ameliorating such subsoils. Yield responses to both treatments were highly significant and stemmed from reductions in subsoil Al and increases in Ca. Root measurements corroborated the fact that the responses were due to root proliferation in the subsoils and consequent resistance to drought stress. Redistribution of roots in the profile in ameliorated subsoils resulted in P insufficiencies being recorded despite high soil test levels of P probably the result of a relatively smaller root surface in topsoil where P had been placed. These results confirm the feasibility of using gypsum and in particular, phosphogypsum as a subsoil ameliorant.

ISSN:0010-3624    

DOI:10.1080/00103628809368014

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Gypsum has been shown to ameliorate subsoil acidity in highly weathered soils. The effects of surface application of phosphogypsum on the chemical composition of five Georgia Ultisol subsoils were investigated in leaching columns. The experiment was designed in such a way as to characterize the leachate leaving the topsoil, the composition of which was substantially changed by the phosphogypsum treatment. Leachates from treated columns were higher in magnesium, potassium, and silicon, although the ionic strength never exceeded that of a saturated gypsum solution. Thus, the ameliorating solution entering the subsoil was different from the solution of phosphogypsum. After leaching, subsoil acidity was ameliorated as evidenced by reduced exchangeable Al and increased Ca in the subsoil. The reduction in Al was consistent with the formation of a solid phase such as alunite. Considerable quantities of Mg and K were leached from topsoils into subsoils. While the subsoil rooting environment may be improved by this treatment, the loss in topsoil fertility may temporarily negate this effect until these nutrients are replaced.

ISSN:0010-3624    

DOI:10.1080/00103628809368015

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Use of ammoniacal N in continuous corn production results in greater acidification of the surface soil layer under conservation tillage. Moldboard plowing results in dilution of acid inputs to greater depth. The objective of this work was to observe soil reaction after a lime application made to a continuous corn experiment initiated in 1970. Four fertilizer N rates (0. 84. 168. and 336 kg N ha‐1) and two primary tillage systems (no‐tillage and moldboard plowing) were used. Lime application was made to half of each plot in 1983. Control of developed acidity was achieved the first year on the plowed soil. This was not the case on the most acid no‐till soil, where both corn dry matter production and leaf Mn concentration also indicated persistence of acidity. Surface lime application resulted in soil pH changes limited to the upper 10 cm of no‐till soil. Shallow incorporation of lime may be needed to more quickly control strongly developed acidity in no‐till soils.

ISSN:0010-3624    

DOI:10.1080/00103628809368016

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Alfalfa (Medicago sativaL. cv Peace) and barley (Hordeum vulgareL. cv Otal) were grown in the greenhouse on three moderately acid soils (pH 4.7 to 5.1). Calcium amendments consisted of adding CaCO3to achieve pH values of 6.0 and 6.7, or CaSO4(gypsum) equivalent in Ca to CaCO3to attain pH 6.7, and a check (nil Ca). Three P treatments were superimposed on each Ca treatment: O, 30 and 60 mg P kg‐1soil. Dry matter yields of both alfalfa and barley were increased by CaCO3and not affected by CaSO4. Phosphate increased yields although soil test P values were medium to high. There was a strong CaXP interaction. The yield increase due to CaCO3and P additions was greatest for the soil with the least amount of soil test P and organic matter, and relatively small when the soils were limed from pH 6.0 to 6.7. Liming reduced Al concentration and ‐increased P concentration in the soil solution. Gypsum increased Al concentration and had variable effects on solution P concentration. Soil solution P concentration and soil pH accounted for 85 percent of the yield variations in barley.

ISSN:0010-3624    

DOI:10.1080/00103628809368017

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Only a few reports have been made on long‐term liming experiments on Ultisols and Oxisols in Africa. This series of experiments on an Ultisol in northern Zambia, beginning in 1978, were used to measure the effects of liming with continuous cultivation in an area which receives about 1200 mm annual rainfall in a 7‐month period. The effects of liming were still present after 8.5 years. Lime applied at 8 t ha‐1reduced soluble Al in the 30–45 and 60–75 cm depths to 1/3 and 1/2 respectively of that in the control; lower rates of lime were less effective at these depths. Changes in pH, exchangeable Ca and Mg, and soluble Al also occurred at the various depths for the lime treatments.

ISSN:0010-3624    

DOI:10.1080/00103628809368018

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The objective was to determine the effect of liming on the net ammonification and nitrification in the field of 26 acid soils during the first year after application. The soils ranged from pH 4.4 to 6.0 and were limed to a target pH of 6.7. The 26 sites were located in Alberta and northeastern British Columbia. Soils were limed in the spring, fallowed and sampled in the next spring. The content of NH4+‐N plus NO3‐‐N in the 0–15 cm layer of the non‐limed treatments varied from 6 to 48 Hg/g (average of 26), while the limed treatment varied from 14 to 89 μg/g (average of 40). The increase in ammonification was negatively related to soil pH and positively related to soil total N (R=0.66**). The proportion of NH4+‐N in the mineral‐N varied among the non‐limed samples, but it was not related to soil pH. The same was true among the limed samples. This field study suggests that for at least a year after liming both the increase of mineral‐N, and variation in nitrification, may complicate crop behavior in field assessment of liming.

ISSN:0010-3624    

DOI:10.1080/00103628809368019

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Reclamation potential of contaminated soil from beneath a sulphur block basepad was evaluated in three 62‐day greenhouse trials. The effect of CaCOs and manure treatments added to pots of soil containing four different levels of total sulphur (<0.1, 4, 9, and 14%) was tested through characterization of soil chemistry and growth of reed canary grass. Results for aboveground biomass determinations and selected soil chemical analyses are reported.

ISSN:0010-3624    

DOI:10.1080/00103628809368020

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The 17‐year growth response of a 45‐year‐old jack pine (Pinus bariksianaLamb.) forest on an acid brunisolic soil to applications of 224 and 448 kg Ca ha‐1(560 and 1120 kg ha‐1of CaCO3) in 1970 was examined. Increases in the level of exchangeable Ca and pH and decreases in exchangeable acidity, in relation to untreated soil, suggest that liming had a modest long‐lasting effect on base saturation of the forest humus. Liming produced significant increases in the amount of ammonium contained and mineralized in humus layers and the Bm1horizon after 15 years, but no changes in the bulk of the mineral soil N were detected. Liming had a negligible effect on nitrification in the soil. It had no effect on pine growth nor did the treatment significantly influence the N concentration in foliage collected prior to the growing season of 1987. The results suggest that in N‐limited jack pine forests, lime‐stimulated N turnover is not sufficient to produce a growth response to N by the trees.

ISSN:0010-3624    

DOI:10.1080/00103628809368021

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628809368022

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628809367973

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor