Zeolite application for enhancing water infiltration and retention in loess soil
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Resources, Conservation and Recycling
34 (2001) 4552
Zeolite application for enhancing waterinfiltration and retention in loess soil
He Xiubin *, Huang ZhanbinInstitute of Soil and Water Conseration, Chinese Academy of Sciences,
Yangling Shaanxi 712100, Peoples Republic of China
Received 16 June 2001; accepted 6 July 2001
Zeolite is a relative abounded mineral resource. Its distinguished properties on cationexchange capacity (CEC), free structural water storage and surface adsorption have a greatpotential application on soil ameliorating. The present research applied the zeolite powder inthe fine-grained calcareous loess soil, and compared rainfall infiltration and soil waterretention of the normal soil with these of treated soil both in laboratory and field. The resultsshow that soil treated with zeolite, compared with the normal soil, could increase infiltrationby 730% on gentle slope land and more than 50% on steep slope land. In addition, thetreated soil could increase soil moisture by 0.41.8% in the extreme drought condition, and515% in general situation. Consequently, it can reduce overland flow (surface runoff) andprotect soil from erosion. And furthermore, can regulate water supply for crops in severedrought conditions. Thus, zeolite has special properties that can be potentially applied towater efficient use for dryland farming. But some technological aspects need scientificinvestigation and experiment before it puts into broad implementation. 2001 ElsevierScience B.V. All rights reserved.
Keywords: Zeolite application; Infiltration; Water retention; Loess soil
The water consumption by agriculture accounts for most part of water resourcesin the continents. Specially, in the arid and semi-arid areas of the world, it
* Corresponding author. Tel.: +86-29-7011861; fax: +86-29-7012210.E-mail address: email@example.com (H. Xiubin).
0921-3449/01/$ - see front matter 2001 Elsevier Science B.V. All rights reserved.
PII: S0921 -3449 (01 )00094 -5
H. Xiubin, H. Zhanbin / Resources, Conseration and Recycling 34 (2001) 455246
accounts, for example, for more than 80% of the total water consumption in thenorthwestern China (Earth Science Division of CAS, 1998). And most part of waterfor agriculture is originated from rainfall. The uneven distribution of rainfall withinyear or between years leads to unstable production of agriculture because of lack ofwater supply. On the other hand, the low soil water infiltration and the highintensity of rainstorm usually produce large amount of overland flow (surfacerunoff), leading to severe soil erosion and nutrient loss, and consequently, leadingto land degradation (Mathur, 1991; He Xiubin, 1995). Therefore, rational using ofrainfall does not only lessen the pressure of water shortage, but also benefits thesustainable development of agriculture. In response to these concerns, there havebeen increasing efforts to develop improved measures to increase infiltrationcomponent of rainfall and decrease the runoff (Rawls et al., 1991).
Soil conditioner is one of the examples. The first chemical soil conditioner wasdeveloped in 1951 and reported in a special edition of Soil Science in 1952 (Bear,1952). Since then, a number of soil conditionals have been marketed. But not allwere effective and most of the successful ones were often too expensive to beapplied in dryland farming (Aagassi et al., 1990; Azzam, 1980). However, before1990s, the soil conditioners were, in fact, a kind of physical soil conditioner, whichmainly focused on the improvement aggregate ability and aggregate-forming pro-cesses, although the mechanism of conditioner and soil inactions were not fullyunderstood. Recent soil conditioner research has directly addressed the effect of soilconditioners on water infiltration, soil erosion and crop performance (Ben-Hur andKeren, 1997; Bowyer-Bower and Bun, 1989; Brandsma, 1997). At the same time,many papers have been published in improved application techniques at lower costs(Aagassi et al., 1990; Ben-Hur et al., 1989). Unfortunately, all the researches haveapplied the artificial chemical materials for the conditioner development, whereasfew attempted to apply the natural ones.
Zeolite is a complicated silicate mineral. But it is different from other silicatemineral by spacious pores and channels within its crystal structure. The silicatetetrahedron (SiO4) is a compromise between electrical neutrality and packingefficiency. To form electrically neutral, stable minerals require other positivelycharged accessory cations. This need for electrical neutrality and accessory cationsleads to the important property of cation exchange capacity. The zeolite in naturalcondition is combined with cations such as Na+, K+, Ca2+ and etc. (Dana, 1977;Navrotsky et al., 1995). It generally has three distinguished properties (Sand andMumpton, 1978): one is great high cation exchange capacity (CEC; ten times morethan that of soil); the other is large amount of free water in the structural channels;and the third is high ability of adsorption (with surface area of about 1150.5 m2/g).These properties have been widely used in inorganic membrane science andtechnology (Burggrafand and Cot, 1996; Yardley, 2000). Recently these propertieshave been applied to environmental science, such as improving water quality(Pirtola et al., 1998) and ameliorating soil (Pan Genxing et al., 1991; Booker et al.,1996; Haidouti, 1997).
The present experimental research aims to use zeolite as a soil conditioner toincrease rainfall infiltration into the soil, enhance soil water storage capacity, and
H. Xiubin, H. Zhanbin / Resources, Conseration and Recycling 34 (2001) 4552 47
bring some sights on efficiently using of rainfall and regulating water supply forcrops.
2.1. Zeolite sample
The zeolite mineral sample is taken from natural zeolite mine. The zeoliteaccounts for about 69% of the total mine material, which is mainly a kind ofmordenite. The sample was abraded into powder, and passed through a 0.25 mmsieve (Pan Genxing et al., 1991). The chemical composition and some fundamentalproperties of zeolite powder are shown in Table 1.
2.2. Soil for experiment
The soil in the laboratory and field are the fine-grained calcareous loess soil. Thesoil organic content was measured as 0.76% by weight, and calcium carbonate(CaCO3) was measured as 8.1%. The texture of these soils is shown in Fig. 1 andFig. 2. The content of 0.050.01 mm fraction is very high, accounting for 46%, andthe clay fraction (0.002 mm) accounts for 24%. Other properties and detaildescription of the soil can refer to Agriculture And Soil On The Loess Plateauwritten by Zhu Xianmo (1989). In the laboratory, soil was prepared by removinggrass turfs and leveling the surface.
Table 1The Chemical composition and some related properties of zeolite powder. The net zeolite accounts for69%, 92% of which is mordenite
Indices of propertiesa Chemical composition (%)
pH 7.8 SiO2 66.05CEC (meq/100 g) Al2O3136.35 12.11Exchangeable K (meq/100 g) 7.12 Na2O 2.12Exchangeable Na (meq/100 g) CaO47.55 3.86Exchangeable Ca (meq/100 g) 1.10K2O46.89
H2O 13.290.54Exchangeable Mg (meq/100 g)Soluble Si (ppm) 474.53 MgO 0.89
121.32Saturation water content (%) MnO 0.32P2O5Capillary water content (%) 0.1787.11Fe2O3 0.11
The powder contents the grains with diameter less than 0.25 mma All data based on n=12 readings.
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Fig. 1. Texture of soil for the experiment in the laboratory.
This research experiment was conducted in microplots in the laboratory withartificial rainfall, and then extended to plots in the field. In the laboratory,aluminum microplots (0.28 m2) were prepared to fill with normal soil and thezeolite-treated soil. A laboratory computer-based rainfall simulator was used. Themicorplots were exposed to a constant rainfall intensity of 2.00 mm/min for anhour under different slope degrees (5, 10, 20). There were three replicated plotsand two replications of rainfall events under each case of slope degree. The runoffamount was measured in the outlets of the microplots. The infiltration componentof rainfall was calculated by the Eq. (1):
Where Ft is the infiltration amount; Rt is the runoff amount; and Pt is theprecipitation.
Fig. 2. Some properties of experimental soil profile in the field.
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Table 2Rainfall partitioning in the normal soil and treated soil at the laboratory
Treatments Infiltration amount of theSlope (degrees) Time of runoff Sediment (kg)first 30 min (mm) beginning (min)
5 26.50Normal 0.04655.5828.33** 0.009***59.53**With zeolite21.50 0.06410 Normal 41.9626.42 0.015***54.70**With zeolite
20 19.22 8.42 0.117Normal12.56** 0.029***29.11**With zeolite
The microplots size is 0.4-m long and 0.7-m wide. The rainfall intensity was 2 mm/min. Results basedon 3 samples for each plot (three replications) in every rainfall event (two replications), totaling 18readings. Significance of results as compared to normal plots, determined using Students t-test.
In the field, two plots (1.57.5 m2) were designated under natural climaticcondition with the slope degree of 15, the surface soil is bare fallow. One was thenormal soil; the other was treated with zeolite. The precipitation and runoff wereobserved. The infiltration component of rainfall was calculated by the Eq. (1).
4. Results and discussion
4.1. Effects on rainfall infiltration
Table 2 shows, in the laboratory, the soil water infiltration of the zeolite-trea