摘要:

Dichromate‐oxidizable and total organic carbon in soils from the major mineral soil areas in Louisiana were measured. The objective was to determine if it is possible to use one correction factor for calculating total from dichromate‐oxidizable carbon for all mineral soil areas in the state or if separate correction factors are needed for each soil area. The recovery of total organic carbon from 179 soil samples from all mineral soil areas using the dichromate oxidation with no external heating (Walkley‐Black) method ranged from 46 to 87 % with a mean of 71 % and a c.v. of 9.8%. An average correction factor of 1.41 for calculating total from dichromate‐oxidizable organic carbon can be used for all mineral soil areas in Louisiana. However, this correction factor will be inaccurate for many individual soils. Although small but significant differences among the recoveries of total organic carbon from some of the different soil areas were observed, the differences are not large enough to warrant using separate correction factors for each soil area, since there is more variation within a soil area than between soil areas.

ISSN:0010-3624    

DOI:10.1080/00103628609367771

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Following B sprays, fruit set increase in ‘Barcelona’ hazelnut was accompanied by a decrease in dry‐matter accumulation for the entire fruiting twig. In unsprayed controls prior to 5 June, leaves constituted 80% of the total dry weight of a fruiting twig. Later in the season (5 Aug.) the percent dry weight was maximum in the nut tissue (66%), followed by leaves (17%), and then husks (13%). Leaves contained 87% of the total B in a fruiting twig early in the season, indicating that the leaf was a major sink for B at that time. Of the net B increases over a 2 months period, 24% was in the leaves, 38% in the nuts, and 37% in the husks. By 5 Aug., compared to other tissues, stem dry matter (3%) and B content (32) was negligible; hence, the stem was of little importance in overall partitioning. Boron sprays did not alter B partitioning in the fruiting twigs.

ISSN:0010-3624    

DOI:10.1080/00103628609367772

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Open pollinated ‘York Imperial’ apple (Malus domesticaBorkh.) seeds were germinated and grown for a period of 7 months in: (1) sand with complete nutrient solutions added; (2) limed and unlimed soil, (3) limed and unlimed soil amended with two different sewage sludges at rates of 25, 50 or 100 dry kg ha‐1. A third composted, lime stabilized sludge was added either sieved or non‐sieved (to remove wood chips) at the same rates. The sludge materials used were: (1) a high metal, composted sludge from Baltimore, MD (BALT); (2) a high Cd sewage sludge (CITY) and (3) a low metal, composted sewage sludge from Washington, D.C. (DC).

ISSN:0010-3624    

DOI:10.1080/00103628609367773

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Some form of deep tillage is required in the coarse‐textured sandy soils of the Southeast in order to attain maximum yield of wheat. ‘Slit‐till’ is a tillage system that modifies plowpans and permits root penetration and proliferation into subsoil horizons. A greenhouse experiment was conducted to determine the effects of calcium nitrate, calcium phosphate, ammonium phosphate, ammonium nitrate, and dolomitic limestone slurry on wheat (Triticum aestivumsp.) root development through the slit of a compacted acid subsoil, and the effects of injection of chemical amendments on the soil chemical properties of acid subsoil. Soil cylinders were prepared using A and B horizons of Marvyn loamy sand (fine‐loamy, siliceous, thermic, Typic Hapludults) soil by placing 56‐cm of subsoil and 10‐cm of topsoil in PVC tubing. A 6‐cm‐thick hardpan was created at the top of the subsoil. Leaf and root concentrations of P were increased by chemical injections in the slit. All amendments increased plant height, but tillering was not affected by chemical amendments. Gypsum blocks placed at 10, 20, and 45 cm indicated a decrease in soil water at the 20‐cm depth 25 days after plant emergence with all amendments except ammonium phosphate. Soil pH was increased and KCl‐extractable aluminum was decreased by dolomitic limestone up to 3.0 cm from zone of injection.

ISSN:0010-3624    

DOI:10.1080/00103628609367774

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Diagnosis and Recommendation Integrated System (DRIS) nutrient ratio norms and critical nutrient limits (CNL) have been used to successfully predict nutrient deficiencies in a number of crops; however, DRIS norms have not been available for rice (Oryza sativaL.). The purposes of these experiments were (1) to test the efficacy of the DRIS and the CNL methods for predicting nutrient deficiencies in rice and (2) to evaluate the potential of foliar fertilization for increasing rice yields. In 1984, DRIS norms were derived for rice Y‐leaves (the youngest mature leaf blade) taken at early internode elongation from a population of high yielding plots and treatments from various Arkansas rice experiments. These norms, and CNL were used in the three 1984 experiments. In 1985, separate sets of DRIS norms were prepared for the medium grain cultivar ‘Mars’ and for long grain cultivars of rice and used in four experiments. In these experiments, Y‐leaf samples were taken and nutrient ratios were determined. Foliar fertilizations, based upon DRIS‐predicted limiting nutrients, were made 5 to S days after sampling. In one experiment in 1984, yields were increased over the control by applying DRIS‐predicted limiting nutrients. In the other six experiments, treatments based on DRIS‐predicted limiting nutrients did not increase yields over the controls. In four of ten cases in which the CNL method predicted N deficiencies, N foliar fertilizations increased yield. However, an N response occurred in three cases in which N was not predicted to be deficient.

ISSN:0010-3624    

DOI:10.1080/00103628609367775

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Sorghum [Sorghum bicolor(L.) Moench] is a potential crop for use in lowland paddy soils following rice in the Philippines. Little is known about the variability in sorghum germplasm with respect to yield potential in these soils, or the alterations in mineral uptake which might occur if late season rains resulted in waterlogging. Eight sorghum cultivars including the most widely used Philippine cultivar were grown after rice under flooded or non‐flooded conditions. Flooding was initiated 30 days after seeding and terminated when most cultivars were at or near the boot growth stage. Flooding markedly reduced dry matter production, and delayed bloom date on the average of 5.5 days. Grain yield was reduced about 57% over all cultivars. Early maturing cultivars were not reduced in days to bloom as much as the late maturing types, and there was a significant cultivar x treatment interaction for both bloom date and grain yield. Later maturing cultivars outyielded the other cultivars at physiological maturity in both flooded and non‐flooded conditions. Concentrations of the major nutrients N, P, K, Ca, Mg, and S were decreased in foliage at the boot stage due to flooding. The only nutrient to fall below published “critical” levels in leaf tissue, however, was N, and plants growing in these conditions showed classical N deficiency symptoms. Iron and Mn concentrations were significantly higher in foliage at the boot stage with flooding, but not high enough to be considered toxic. Most differences observed at boot still existed at maturity, but of less magnitude. Marked variability existed in the response among cultivars to waterlogging. It would appear that flooding tolerant genotypes could be selected which would improve existing cultivar choices for use in these difficult soils.

ISSN:0010-3624    

DOI:10.1080/00103628609367776

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The ratio between non‐humified and humified fractions in pyrophosphate extracts is shown to vary during maturation of sewage sludge. The ratio is higher than 1 in the raw materials but lowers at 1 or less than 1 with the aging of sludge and is assumed to reflect quantitatively the degree of stabilization of organic matter in the sludge. Analytical isoelectrofocusing (IEF) experiments showed that humified fractions in raw sludge focalize only in the pH gradient regions lower than 5.0, whilst in older sludge samples a progressive strengthening of bands occurs in the region between pH 6.5 and 5.0, approaching at least partially IEF patterns of soil organic matter. IEF patterns are suggested to reflect the stabilization of organic matter in sewage sludge from a qualitative point of view.

ISSN:0010-3624    

DOI:10.1080/00103628609367777

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effects of varying phosphorus (P) and sulphur (S) supply on the dry matter production, height growth, foliage type, nutrient content and nutrient composition of blackwood seedlings were examined in a fractional, factorial experiment with 12 levels each of P and S in 29 treatments.

ISSN:0010-3624    

DOI:10.1080/00103628609367778

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628609367770

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor