Synthetic macronet hydrophilic polymers as soil conditioners. I. kinetic characterization of macro‐net sulfonated polystyrene resins

Abstract

Polystyrene‐based macronet polymers, bearing ionic groups on their chains, have shown properties that can characterize them as soil conditioners. This study is based on their capability to retain water in their structure in amounts that equal many times the polymer's dry weight. The kinetics of water retention indicated that the velocity with which they act in polymer‐soil systems is high. The water capacity as well as the apparent density of the polymer‐soil mixtures was determined. At the same time, the performance of these mixtures was identified using soil column experiments under free water flow. The final values for the mixtures’ water capacity were found to depend on the swelling ratio and the water capacity of the polymer itself.     

Monitoring the combined action of controlled‐release fertilizers and a soil conditioner in soil

Abstract

The combined action of a soil conditioner and a controlled‐release fertilizer was followed by conducting soil column leaching and tomato growth experiments. The change in soil water‐holding capacitiy and the release of potassium sulfate (K₂SO₄) from conventional and controlled‐release forms was evaluated using leaching experiments in soil columns. Tomato growth was followed by the comparison of biomass yields on a dry matter basis with experiments where different combinations of controlled‐release or conventional fertilizer rates and soil conditioner applications. It was demonstrated that the combined usage of controlled‐release fertilizers and soil conditioners increased tomato yield and enhanced the nutritional status of the tomato plants in comparison to conventional fertilizer materials.     

Soil application of a hydrophilic conditioner in relation to moisture,irrigation frequency and crop growth

Abstract

A wide range of synthetic and natural materials can act as amendments to enhance soil physical properties. Novel materials purporting to be conditioners need to be agronomically evaluated prior to adoption for general use. Of particular concern in semi‐arid regions are those that influence water relations in sandy soils. A polyacrylamid hydrogel, “Aquastock”, was tested in the laboratory for moisture retention under varying environments to simulate field conditions, and in relation to soil properties. A companion greenhouse study considered the influence of both rate and method of application on cucumber yield, and on irrigation frequency. The material increased available water and reduced permeability, especially in the sandy soil. Moisture release under varying soil pressure or matric potential was favorably influenced by the conditioner. The material significantly increased fruit yield and related crop parameters as well as reducing the number of irrigations required; complete mixing with the soil volume was more effective than partial mixing. “Aquastock” appears to have potential in semi‐arid areas and with protected high value cropping. Commercial and economic evaluation is warranted.     

Leak-preventing effect of synthetic soil conditioners in paddy field

Synthetic soil conditioners have been studied by many soil scientists, but their studies were mainly on the formation of the water-stable aggregate of soils. But it may be possible that, if synthetic soil conditioners, the water-soluble polymers, are spread on the plowsole of the leaky paddy field, the leakage of water is prevented by the thin layer of the polymer formed by the swelling with irrigation water.     

Soil micromorphological and physical properties after application of composts with polyethylene and biocomponent-derived polymers added during composting

Composts are considered to be one of the best soil amendments. However, the effects of composts with added polymeric materials on soil physical,hydraulic, and micromorphological properties have not been widely discussed. Changes in soil physical properties influence the numerous services that soils provide. We studied the impacts of composts with the addition of three different polymers(F1–F3) produced from polyethylene and thermoplastic corn starch on the physical, hydraulic, and micromorphological properties of two soils, a Cambic Phaeozem and a Luvic Phaeozem. Applying composts with polymers had limited or no significant effect on soil bulk density and porosity, but increased the field water capacity by 18%–82% and 3%–6% and the plant-available water content by 15%–23% and 4%–17% for the Cambic Phaeozem and Luvic Phaeozem, respectively. The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem. It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate. Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.     

Water holding capacity and evaporation of calcareous soils as affected by four synthetic polymers

Abstract

Four soil conditioners, Broadleaf P4, Agrihope, Aquasorb, and Hydrogel, were used in a laboratory study to evaluate the effectiveness of these polymers on water holding capacity (WHC), evaporation, and water conserved in calcareous sand and loam soils. Four rates of these polymers, 0.0, 0.2, 0.4, and 0.6% (on dry weight basis), were added to these two soils. All treatments were irrigated weekly to 60% WHC for a total of 16 wetting‐drying cycles. An increase in polymer applied increased the WHC, decreased evaporation, and as a result increased the amount of water conserved in both the soils. Broadleaf P4 was more effective even at lower rates. The effectiveness of the polymers used could be arranged in the following order: Broadleaf P4 > Aquasorb > Agrihope > Hydrogel.     

Water retention of light expanded clay amendment

Abstract

Shallow‐drained horticultural soils utilized in containers, sporting areas, and landscape sites tend to retain excess water and thereby be poorly aerated as a consequence of capillary retention following irrigation or precipitation. This problem is usually corrected by soil physical amendment with coarse‐textured particulates to add large pores which drain and provide adequate aeration. A variety of materials are used for soil physical amendment. This study examined the water retention of one of the newer amendments used for this purpose, light expanded clay amendment (LECA), relative to its use in shallow‐drained soils. Although LECA is a porous material, its contribution to soil physical properties when used as an amendment were found to be similar to non‐porous amendments such as river sand or gravel because the internal water is not readily available for plant use.     

Evaluation of pumice as a perlite substitute for container soil physical amendment

Abstract

Shallow‐drained horticultural soils utilized in containers, sporting areas, and landscape sites tend to retain excess water and be poorly aerated as a consequence of capillary retention following irrigation or precipitation. This problem is usually corrected by soil physical amendment with coarse‐textured particulates which add pores sufficiently large to drain and provide adequate aeration. A variety of materials are used for soil physical amendment. One of the most common and successful amendments is perlite. This study examined the feasibility of using pumice, a very similar mineral, as a substitute for perlite in soil amendment.

The physiochemical properties of pumice important to its use as a container soil amendment were found similar to those of perlite.     

Organic matter in volcanic soils in Chile: Chemical and biochemical characterization

Abstract

Determinations were made of total soil organic matter (SOM), stable and labile organic fractions, biomass carbon (C), and chemical composition of several humus‐soil‐fractions in Chilean volcanic soils, Andosols and Ultisols. Their physico‐chemical properties and humification degree at different stages in edaphic evolution were also assessed. In addition, organic matter models were obtained by chemical and biological syntheses and the structures and properties of natural and synthetic humic materials were compared with SOM. Results indicate that Andosols have higher SOM levels than Ultisols, but the fraction distribution in the latter suggests a shift of the more stable fractions to the more labile ones. Moreover, contents of humines, and humic and fulvic acids suggest that Chilean volcanic soil SOM is highly humified. On the other hand, among the SOM labile fractions, carbohydrate and biomass are about 15% of the SOM which are one of the most important fractions in soil fertility.     

Determining soil and water sodicity from electrode measurements

Abstract

A method is presented for estimating the sodium adsorption ratio (SAR) of the saturated soil‐paste extract from three electrode measurements made directly in the saturated soil‐paste. An analogous method is presented for the determination of the SAR of extracts and solutions solely from electrode measurements made in the extract or solution. Both methods are carried out without the use of pH and ionic strength buffers. The methods were tested on a widespread range of salt‐affected soils and their extracts; they are deemed suitable for field applications in the diagnosis, screening, and classification of sodic soils and waters.     

Evaluation of two soil conditioners for limiting post‐fire erosion as part of a soil conservation strategy

Soil conservation is a major concern for catchments affected by forest fires. The lack of vegetation cover and the development of soil water repellency increase the risk of topsoil erosion. This paper evaluates two soil conditioners (a wetting agent and a polyvinyl acetate) for limiting overland flow and erosion in inter‐rill areas. Unburned and burned soil samples were treated with one or both soil conditioners. The effects of these treatments on run‐off, water retention, erosion and plant growth were assessed using laboratory rainfall simulations. Polyvinyl acetate had little impact on water retention but was effective in reducing soil loss. The surfactant had little impact on water run‐off or soil loss but substantially improved water retention and plant biomass production. Application of soil conditioners on post‐fire areas could be a valuable technique in a soil conservation strategy. To maximize their benefits, soil conditioners could be applied with seeding using hydroseeding techniques and be limited to particular areas, such as paths and roadsides. Laboratory results indicate that field testing should also be carried out.     

Synthetic Fibers as Indicators of Municipal Sewage Sludge,Sludge Products,and Sewage Treatment Plant Effluents

Because of concerns regarding health, safety, and aesthetics, a test that identifies the presence of sewage sludge or its products (biosolids) in commercial materials such as soil conditioners and composts would be useful. This test could also trace the effluent plume from a sewage treatment plant. We have discovered that synthetic fibers serve as such an indicator. Synthetic fibers are abundant in sludge, sludge products, and sewage treatment plant effluents. The fibers evidently are introduced from clothes-washing machines and survive the sewage treatment process. Synthetic fibers were identified using polarized light microscopy, which provided a simple, rapid method for determining the presence or absence of municipal sewage sludge or its products. False positives or false negatives have not occurred with any of the materials examined so far. We also monitored synthetic fibers in surface sediments of Huntington Harbor, Long Island, NY, a harbor receiving the effluent from a trickling filter sewage treatment plant. Fibers generally decrease in size and abundance with distance from the source. In Oyster Bay Harbor, Long Island, an advanced sewage treatment plant is operated with a final microfiltration step. Synthetic fibers are less abundant in the sediments of this harbor.     

Effects of polyacrylamide,biopolymer and biochar on the decomposition of 14C‐labelled maize residues and on their stabilization in soil aggregates

The efficacy of applying plant residues to agricultural soils as a carbon (C) source for microorganisms and C sequestration is dependent on soil physiochemical properties, which can be improved by aggregation using soil conditioners. However, no attempt has been made to assess the effects of soil conditioners such as biochar (BC), biopolymer (BP) or polyacrylamide (PAM) on plant residue decomposition. We assessed the effects of BC, synthesized BP and anionic PAM on the decomposition of ¹⁴C‐labelled maize residues and on their stabilization in aggregate fractions in sandy and sandy loam soils. Polyacrylamide and BP were applied at 400 kg ha^?1 and BC was applied at 5000 kg ha^?1, and the soils were incubated for 80 days at 22°C. The conditioners improved the physical and biological properties of both soils, as shown by a 24% increase in the 1–2 mm aggregates. Biochar and BP accelerated the decomposition of plant residues as indicated by ¹⁴CO₂ efflux, and resulted in reduced stabilization of residues in both soils relative to that observed in the control and PAM treatments. The reduction in ¹⁴C incorporation and C stabilization in the BC‐ and BP‐treated soils was observed mainly in the < 0.25‐mm aggregates. This was confirmed by reduction of activity of hydrolytic enzymes (β‐cellobiosidase and β‐glucosidase). Decomposition of plant residues in sandy soil was more sensitive to BP and PAM application than that in sandy loam soil. Improved soil structure after applying BC and BP increased aeration and decreased the contact between plant residues and mineral soil particles and consequently accelerated plant residue decomposition and reduced C sequestration.     

Soybean response to the application of several elements on a low‐manganese soil

Abstract

Certain soils in the Lower Atlantic Coastal Plain are Mn‐deficient and because of their inherent properties, deficiencies of other elements might be expected. The response of soybean [Glycine max (L.) Merr. cv. ‘Ransom'] to annual soil applications of B, Cu, Fe, Mo, S, and Zn with and without Mn was examined. The study was conducted on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) in 1975, 1976, and 1977. Seed yields, and soil and plant tissue concentrations of certain of the applied elements were determined. Soil pH increased from 6.4 in 1975 to 7.0 in 1977 as a result of lime applications.

Of the seven elements studied, only Mn significantly increased soybean seed yield compared to the check. Leaf concentrations of the respective elements were higher where the element was added than they were in plants grown on the check plots. In 1977, after three years of elemental additions, plant concentrations of Mn, Cu, and Zn were higher, relative to checks, than in 1975. In 1977, with the higher soil pH levels, plants from check plots had lower concentrations of Mn, but unexpectedly equal levels of Cu and higher levels of Zn than in 1975. This unexplained increase in plant Zn was also found in Other experiments in the same field during the same time period. Double acid extracted more soil Mn, Cu, and Zn than did DTPA from similar treatments during all three years. The DTPA‐extractable soil Mn correlated much better with plant Mn than did double acid Mn values, especially over years where a change in soil pH occurred. Correlation coefficients comparing extractable soil versus plant values for Cu and Zn data combined over years were higher for double acid than DTPA, although coefficients for the Cu and Zn data were still generally much lower than for the Mn data.     

有机营养功能型土壤改良剂对灰棕荒漠土的改良效果

[目的]进行有机营养功能型土壤改良剂配方筛选,研究灰棕荒漠土改良效果和杂交饲用甜高粱经济效益,解决灰棕荒漠土保水、保肥能力弱,有机质含量低,作物产量低而不稳的瓶颈问题。[方法]选择甘肃省酒泉市肃州区的灰棕荒漠土,采用田间试验的方法进行研究。[结果]不同梯度有机营养功能型土壤改良剂施用量与灰棕荒漠土孔隙度、团聚体、持水量、有机质、速效氮磷钾、杂交饲用甜高粱经济性状和产量呈正相关关系,与灰棕荒漠土容重和pH值呈负相关关系。施用有机营养功能型土壤改良剂与施用传统化肥比较,灰棕荒漠土容重和pH值分别降低4.10%和8.27%;总孔隙度、毛管孔隙度、非毛管孔隙度、总持水量、毛管持水量和非毛管持水量分别增加3.63%,3.60%,3.67%,3.63%,3.60%和3.67%;有机质、碱解氮、速效磷和速效钾分别增加7.03%,0.37%,0.33%和0.29%;真菌、细菌、放线菌、蔗糖酶、脲酶、磷酸酶和多酚氧化酶分别增加121.42%,34.69%,20.00%,61.79%,45.37%,36.00%和63.23%;杂交饲用甜高粱穗粒数、穗粒重、百粒重、产量、施肥利润和投资效率分别增加6.38%,4.17%,4.42%和4.04%,2 390元/hm2和0.40元/元。[结论]施用有机营养功能型土壤改良剂,有效地改善了甘肃省河西走廊灰棕荒漠土理化性质,提高了持水量和杂交饲用甜高粱产量。     

Control of soil solution interferences in an automated nitrate method

Abstract

An AutoAnalyzer method for nitrate nitrogen based on hydrazine reduction followed by diazotization was re‐examined after certain soil solutions had given poor recoveries. Modifications to the reaction parameters, particularly in the reduction stage improved the recovery of nitrate as nitrite. Soluble organic compounds in the samples were more critical than inorganic salts, but the proposed method allowed tolerance of up to 30 mgl^‐1 total organic carbon. Concentrations of various inorganic ions in soil solutions and natural waters were usually below the limits shown to be critical for the improved method.     

Release of soil phosphate by sequential extractions as a function of soil properties and added phosphorus

Abstract

A study of sequential phosphate (P) extraction by water and iron oxide‐impregnated paper strip procedures was carried out on three Italian soils ranging widely in soil characteristics and enriched with three rates of fertilizer P. The degree of change was dependant on P addition, soil P properties, and type of extraction. For the Fe‐oxide strip procedure, a greater release of P than for water extraction was observed for soils with and without added P. At a given level of added P, more P was released from the soil with the lowest P sorption index (SI). However, at a given level of NaHCO₃‐extractable P, less P was released from the soil with lower SI than from soil with a higher SI, indicating that a greater available P content was necessary for low P sorbing soils to maintain a given rate of P release. The variation of SI accounted for 96% and 92% of the variation in amount of water‐extractable and Fe‐oxide strip P at a given P addition. Furthermore, SI accounted for 97% and 98% of the variation in water‐extractable and Fe‐oxide P at a given increase in available soil P. Inclusion in a soil testing program of an estimate of the P Sorption Index, that accounts for the overall effect of soil properties affecting sorption in soils (clay content and type, iron and aluminum oxide content, surface area, etc.), may improve fertilizer P requirements for optimum crop growth for certain soils.     

Edaphic properties and horticultural applications of some common growing media

Abstract

Landscape plantings, especially in urban situations, often requires different growing media to improve soil physical and chemical qualities or to use them as surrogate soil. A wide selection of materials, organic and inorganic, natural and synthetic, are available. Whether used alone or as amendments in a soil mix, a good understanding of their edaphic properties can provide an objective basis to make recommendations on the types and quantities to be adopted. The lack of relevant published information, however, restricts their rational use. This study evaluates 25 samples obtainable commercially in Hong Kong with reference to 17 edaphic attributes, and interprets the results mainly with reference to tropical horticulture.     

Chemical equilibrations with soil buffer systems as bases for future soil testing programs

Abstract

The soil has mechanisms which serve as buffers or ionic reservoirs which remove nutrient ions from and return them to the soil solution and thus regulate their availabilities to higher plants. Yet relative amounts of each type of cation‐exchange bond are evidently so different from soil to soil that basic cation saturation ratios per se seem unimportant to the well‐being of a crop. Indeed, it appears that instead we should concentrate on sufficiency levels of each basic cation.

Since the above‐mentioned mechanisms buffer the soil available P and K levels as well as pH level, we have developed alternative usages for existing soil tests which seem quite promising as bases for improving the accuracy of lime, and P and K fertilizer recommendations for obtaining near‐maximum yields of crops.     

From marl to rock powder: On the history of soil fertility management by rock materials

The ancient practice of marling and the recent application of rock powder to soils are interventions into the orogenic energy budget of soils. Both are slow‐release, long‐term fertilizers or better, soil conditioners. Marls and their uses are reviewed by a study of knowledge and practices from the 1st century AD to the 1800s, for rock powders, a review of the recent theoretical and experimental literature is presented. Under pre‐industrial conditions, paucity of energy prevented the wide‐spread use of such materials, today they are marketed as by‐product of industrial operations. For marls and rock powders alike, their positive effect depends to a large extent on the soil matrix to which the minerals are applied, on the cultivar, and the specific type of applied material. Drawing parallels between the two materials, we suggest that the long‐term experience with marls could be used to study the effects of rock powders, as duration of experiments with these is most often too limited to allow conclusions.