WM 2} \ l ) \ HM '1 ‘l M ‘x I | ‘ I ‘ 123 862 ABSORPTION OF BORON BY MICHiGAN SOILS Thesis for the Degree of M. S. GARRY WELUAM ROWE 1977. ABSTRACT ABSORPTION OF BORON IN MICHIGAN SOILS BY Garry William Rowe An investigation was conducted to determine the extent to which Michigan soils may adsorb B. With an increasing interest in using soil as a renovator of waste- water, the presence of B in wastewater could be a poten- tial hazard to plant growth. Undisturbed soil cores of a Lenawee loam (Mollic Haplaquept), Brookston loam (Mollic Ochraqualf), and a Metamora sandy loam (Aguic Hapludalf) were collected from a small watershed on the site of the Water Quality Manage- ment Project at Michigan State University. Soil series were split into replications of topsoil and subsoil. An apparatus was constructed to apply a 1.13 mg/liter B solution to the soil cores following a rate and schedule of 1.27 cm/hour for four hours on two days each week. By graphical and soil analysis the amount of B adsorbed was determined. Less than 1 Hg B/g of soil was adsorbed in each soil and at each depth. There were slight adsorption Garry William Rowe differences among soils and no differences between depths. The limited adsorption was attributed to an acid soil pH and low extractable Fe and Al. Since soils had little retention capacity for B, an early equilibrium state between soil and the applied wastewater was expected. Under these conditions plants may be subject to B concen- trations found in the wastewater which may be toxic to plant growth if at sufficiently high levels. ABSORPTION OF BORON BY MICHIGAN SOILS BY Garry William Rowe A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop and Soil Sciences 1977 ACKNOWLEDGMENTS The author wishes to express his gratitude to Dr. J.E. Hook for his help and advice throughout the study. This appreciation is extended to Dr. B.D. Knezek and Dr. B.G. Ellis for their advice and suggestions regarding the experiment and soil analysis. An appreciation is also extended to Dr. C. Cress for his help in the statistical analysis. ii TABLE OF CONTENTS LI ST OF TABLES O O O O O O O O O O O O 0 LIST OF FIGUMS O C O O O O O O O O O O INTRODUCTI ON C O O C O O O O O O O O O 0 LITERATURE REVIEW . . . . . . . . . . . Reactions of B in Soil. . Adsorption of B in Soil . Factors in B Adsorption . Physical. . . . . . . . Chemical. . . . . . . A Two-Step Mechanism for B Adso rpt' on “THODS AND MATERIALS 0 O O O O O O O O Leaching Experiment . . . . . . . . . Soil Analysis . . . Graphical and Statistical Analysis. . RESULTS AND DISCUSSION. . . . . . . . . SUMMARY 0 o o .0 ‘ o o o o o o o o o o o 0 LIST OF REFERENCES 0 O O O O O O O O O 0 APPENDIX. 0 o o o o o o o o o o o o o 0 iii Page 0 O O O O O O O H P‘ be I5 lb Hmmmunb uh H o 0 NM Ho LIST OF TABLES Table 1 Physical and Chemical Properties of the Soil. . . 2 Calculated Values of B Adsorption from Graphical and Soil Analysis . . . . . . . . . . . . . . . 3 Analysis of Variance of the Breakthrough Points of Br and B--Main Effects and Interactions Calculated on the Unweighted Cell Means . . . . 4 Mean Values of the Breakthrough Points of B and Br Curves . . . . . . . . . . . . . . . . . 5 Analysis of Variance of Graphical Analysis Using Mean Calculated Adsorption Values . . . . 6 Analysis of Variance of Soil Analysis Using Mean Calculated Adsorption Values . . . . . . . Appendix I Complete Data of Physical and Chemical Properties of the Soils. . . . . . . . . . . . . . . . . . iv Page 15 25 26 27 28 28 41 LIST OF FIGURES Figure Page 1 Species of B in solution at various pH values. . . 13 2 Schematic diagram of the system used to deliver the leaching solution to the soil columns and collect the effluent . . . . . . . . . . . . . . l7 3 Diagram of soil column and attachments used to deliver leaching solution to soil. . . . . . . . 18 4 Boron and bromide breakthrough curves for the Lenawee loam topsoil abbreviated to show the breakthrough points and the area used to calculate boron adsorption . . . . . . . . . . . 24 5 Boron and bromide breakthrough curves for the Lenawee loam topsoil . . . . . . . . . . . . . . 31 Appendix II-l Boron and bromide breakthrough curves for the Lenawee loam subsoil . . . . . . . . . . . . . . 42 11-2 Boron and bromide breakthrough curves for the Brookston loam topsoil . . . . . . . . . . . . . 43 11-3 Boron and bromide breakthrough curves for the Brookston loam subsoil . . . . . . . . . . . . . 44 11-4 Boron and bromide breakthrough curves for the Metamora sandy loam topsoil. . . . . . . . . . . 45 11-5 Boron and bromide breakthrough curves for the Metamora sandy loam subsoil. . . . . . . . . . . 46 INTRODUCTI ON The use of soil in the treatment of wastewater has become increasingly popular. Therefore, every aspect of wastewater application on soil and its environmental impact should be carefully examined. Depending upon the concentrations found in the wastewater and the environ- mental conditions, B could be a limiting factor for application of wastewater on agricultural land. Industries that have used B extensively include glass manufacturing, metal production, agricultural chem- icals, leather production, cosmetics, photography, soaps and many more. This usage results in a significant amount of B being discharged into the wastewater system. Concen- trations of B in wastewater vary over a wide range depend- ing on the effluent source and treatment. Concentrations of 0.5 mg/liter to 1.0 mg/liter are common, but concen- trations may reach as high as 4.0 mg/liter (22, 30, 43). For many crop species in the sensitive and semi-tolerant category, 4.0 mg/liter is above permissible limits for B concentrations in irrigation water (39). Eaton (9) has shown that when soil and water are in equilibrium, B con- centrations in the soil solution are equal to that of irrigation water. The effect on plant growth can be pre- dicted from the concentration in the applied water. If the soil has a small capacity to adsorb B, the equilibrium between B in the soil and irrigation water may be quickly established. Plants would then be subject to B levels found in the applied water. Boron has a narrow range of concentration in soil solution where it is adequate for plant growth and where plant toxicity begins. Eaton (8) found that with sensi- tive plants injury began at l to 5 mg/liter of B in solution. This includes most citrus crop species such as lemon (Citrus limonia osbeck) and peach (Prunus pgrsica (L.) Batsch). Semi-tolerant crops showed toxicity symptoms when B concentrations were 5 to 25 mg/liter, which include corn (Egg $222.91) and alfalfa (Medicago sativa L.) Tolerant crop ranges were 10 to 25 mg/liter and include sweet clover (Melilotus indica (2.) All.) and sugar beet (Beta vulgaris var. crassa Alef.). Tolerance of plants to B have also been shown to depend on the rate at which B is adsorbed by the plants (32). Transpiration in the plant appears to be the con- trolling factor in B uptake (23), and toxicity symptoms appeared in the leaf where B would be localized by the transpiration stream. With the plant acting as a sink taking B from the applied wastewater, relatively low con- centrations, such as l mg/liter, could still produce a toxic condition in the plant. Neary, Schneider and White (22) found that when irrigated with wastewater low in B (0.51 to 0.91 mg/liter), toxicity symptoms appeared in. red pine (Pinus resinosa Ait.). This toxic condition was attributed to site loading of B in the soil, however, this may have been caused by direct absorption of B from the wastewater by the plant. With limited adsorption of B by the soil, this condition could be produced in a relatively short time. Little is known about the retention capacities of B in Michigan soils. Most of the studies have been on soils in the Western and Southwestern portions of the United States, as well as in Mexico and Hawaii. Much of this work has also been done on soil fractions rather than on undisturbed soils. This study was conducted to determine the extent to which Michigan soils adsorb B. The principal objective was to determine how much B would be adsorbed by the soils and how quickly equilibrium was established between the soil and applied solution. LITERATURE REVIEW Reactions of B in Soil Once B is introduced into the soil in fertilizer or irrigation water, it may be taken up by plants or micro- organisms. It may also precipitate in or react with the soil, or it may be leached from the soil profile. Most B fertilizers are expected to hydrolyze to boric acid (H3B03) and at pH ranges common in soils the predominate form is undissociated H3303 (18). Likewise, Wilcox (44) has also shown that B in sewage is mostly undissociated H3B03. Because B levels in soil are quite low and most borate compounds are very soluble, precipitation of a borate salt should not occur unless evaporation exceeds rainfall and irrigation. From the standpoint of potential toxicity problems, ‘ the amount of B retained or adsorbed in the soil may be one of the most important factors. For this reason, this study was devoted to adsorption of B. However, effects due to a plant actively growing in the system, along with leaching losses and runoff, cannot be ignored under actual field conditions. Adsorption of B in Soil Various investigations have shown that B applied to soil in irrigation water or as fertilizer was adsorbed or fixed (2, 3, 13, 14, 21, 25, 31, 37). Some work has also shown that B is fixed more easily than it is removed by leaching. Possible mechanisms for B adsorption include ion exchange, molecular adsorption, uniting with diols in organic matter, and entrance of B into clay lattices. Various factors have also been found to influence B adsorption. These included temperature, soil texture, soil drying, time, amount of B added, clay type, organic matter, pH, and the presence of Fe, Al, and Mg hydroxides. Factors in B Adsorption Physical Probably the most significant physical factor for B adsorption in soils was texture. Generally, fine tex- tured soils were reported to adsorb more B than coarse (2, 13, 21, 24). Hatcher, Bower and Clark (14) found that the sur- face area of soils was significantly correlated with B adsorption and only surface hydroxides were active in adsorption. Couch and Grim (7) found that with illite clays, the Specific surface area of the clay was the strongest factor in B adsorption. Calculating B adsorp- tion on a per unit area basis showed that different illite clays fixed the same amount of B. Also, by wet and dry treating the clay, breakdown of the mineral occurred and exposed more surface area for adsorption. Parks (27), using a fine sandy loam, also increased B fixation by increasing drying cycles and reduced the amount of hot-water extractable B. Eaton and Wilcox (9) found that soils originally low in their capacity to fix B, had increased capacity upon drying. Other studies have shown similar results with wet and dry treatments, and most researchers have attributed the increased B adsorption to the breakdown of primary and secondary minerals which exposed more surface area for adsorption. Chemical Many studies have found that pH of the equil- ibrated solution had a very significant affect on the amount of B adsorbed. Sims and Bingham (34) found a striking dependency of pH upon B adsorption in clays and hydroxy Fe and A1 materials. Maximum retention was obtained at pH values of 8.0 to 9.0. Work on soils from Mexico and Hawaii (3) revealed similar relationships between pH and maximum B adsorption. Another study on Hawaiian soils (25) resulted in similar findings when pH was increased to 8.0 and 9.0. Hingston (15) working with clay also found that B retention depended largely on pH. Hatcher, Bower and Clark (14), working with soils, found that B adsorption was enhanced at higher pH levels. Some researchers hypothesized that higher pH resulted in increased formation of borate ions (B(OH);). The B(OH); ion is the favored species for adsorption, and adsorption therefore increases with increasing pH up to a pH of 9.0. Above the pH of 9.0 adsorption rapidly decreases due to competition with hydroxl ions, and hydrous oxides also take on a negative charge resulting in repulsion of the B(OH)Z anion. Some studies have also shown that salt content and salinity may influence B adsorption. Fleet (10) kept the B concentration of a solution applied to illite clay con- stant, and varied the salt content. A two-fold increase in adsorption was found by increasing the salinity from 1.07 to 34.3 percent. Kemp (17) found that in the presence of a neutral salt, especially with hydrated cations, the dissociation of H3B03 increased. Increasing salinity and greater dissociation of H3B03 would then result in more B(OH)Z ions for adsorption. All the studies showed a wide range of B concen- trations being applied to soil or clay. Some investiga- tions have found that increased concentrations of B in the applied solution increased B adsorption. Fleet (10) kept salinity constant and noted an increase in B adsorbed in illite clay as the B concentration increased in the applied solution. Eaton and Wilcox (9) obtained increased B fixation with each increase in B concentration. A proportional decrease was obtained as the concentration exceeded 10 or 15 mg/liters. Parks (27) found that only at lower concentrations did the percent of B fixed increase as concentration increased. Certain materials in soil organic matter may have an affinity for B. Parks and White (29) found that humus had an affinity for B, but that it depended on the type of humus material. They suggested that fixation may result from uniting with diols in organic matter. In contrast to this Sims and Bingham (36) reported a negative correlation between B retention and organic matter content. Harada and Tamai (11) found a significant correlation between B adsorption and organic matter of soils, but upon destruction of the organic matter an increase in adsorption occurred. This was attributed to metals released from the organic matter and forming hydroxyl groups available for adsorbing B. While organic matter may have some affinity for B, it may also complex metal compounds that otherwise would fix B. Decomposing organic matter should increase adsorption. A majority of the research has indicated that the amount of B adsorbed by soil is related to the amount of Fe, Al, and Mg hydroxides. Sims and Bingham (35) found that Fe and Al hydroxy compounds appeared to be responsible for most of the B retained in clay minerals. Hydroxy Al compounds were more effective adsorbers than hydroxy Fe compounds. They suggested reactions involving the B(OH); ion exchanging for a hydroxyl ion (Equation 1), or becoming the end member of a hydroxy Fe or A1 polymer (Equation 2). OH \m// /’ - M + mom4 /MO\ \ Og\/ (2) + B(0H)4 \/‘” 3\ \MOHMQ/\/H\B/OH OH- /W\/\O{\H An additional reaction given was analogous to the formation of the borate-diol complex (Equations 3 and 4). (3) R R - C - OH | + B(OH)4 R - f - OH R (4) OH OH \M/ \M \B(OH) ‘1‘ R-C-O OH | ::B(: + ZHZO R-Cli-O OH R OH O OH \ / \/ \/ /M\ /M\ /B\ +2H20 O O OH 10 Another study by Sims and Bingham (36) revealed that the hydroxy Fe and Al compounds are dominate over clay minerals in determining B retention of layer silicates. The data also showed that retention characteristics may be conditioned by the clay mineral species present. Research by Harada and Tamai (11) indicated that A1203 and Fe203 contents were highly correlated with B adsorption in soil. However, when A1203 and Fe203 were removed from the soil high B adsorption still occurred. This high B adsorption was due to the clay fraction of the soil. Soil clay may have a large affinity for B, but this adsorption ability may be greatly masked by A1203 and Fe203 on the clay surface. Bingham and Page (3), working with amorphous soils from Mexico and Hawaii, found a significant correlation between B adsorption and SiO2 plus A1203 content, but a higher correlation was found with A1203 alone. Hatcher, et a1. (14) also showed that for a wide range of soils B adsorption was highly correlated with surface area and citrate-extractable A1. Rhoades, Ingualson and Hatcher (33) found that with arid soils, silt and sand fractions had appreciable B adsorption capacities. This appeared to be due to clusters or coatings of Mg hydroxide on weathered surfaces of ferromagnesium material. A significant correlation was found between various minerals high in Mg hydroxy coatings 11 and with B adsorption. These minerals were also low in Fe and A1 content indicating the importance of the Mg material. Most of the studies point to Al, Fe and Mg hydroxides as being key factors in B adsorption in soils. Consideration of these compounds is important in predicting how a soil will react to B applied as a fertilizer or in irrigation water. Bingham and Page (4) showed that the adsorption of B appeared to be distinctly different from that of other anions which are more common in soils. Maximum adsorption of 804, P04, C1, and N03 was found under acid conditions while maximum B adsorption occurred under alka- line soil conditions. Because of a difference in behavior of B with these other anions present, no competition with them was expected. A Two-Step Mechanism for B Adsorption Couch and Grim (7) pr0posed a two step mechanism from their results with illite clays. The first step was an initial rapid adsorption of B(OH)Z onto the clay mineral surface. With illite clays this might occur on frayed edges of the illite flake. The next step was diffusion of B into the interior of the clay crystal. Fleet (10) proposed a similar mechanism involving an initial chemical adsorption followed by B installation into the tetrahedral lattice sites. This first step 12 probably proceeded quite rapidly and the second step was slower. In this second step B might replace Al or Si as it migrates into the clay tetrahedral lattice sites. Data from Parks and Shaw (28) also agreed with the con- cept of B being fixed by entrance of B into the clay lattice. Reports appear to support this two step mechanism. First there was an initial rapid adsorption by surface sites such as Al, Fe, or Mg hydroxide compounds followed by a slower process of migration to sites in the clay lattice. Based on the reviewed literature, the major soil factors involved with adsorption of B include pH and the presence of Fe and A1 oxyhydroxides. Undissociated H3303 is the predominate form of B expected in soils, but the borate ion, B(OH)2, is the favored species for adsorption. The adsorption process may be represented by the following diagram: K = 5.8 x 10'10 / .- B(OH)3 + 1130“ B(OH)4 + H limited V ‘ \‘\‘ \ \ k / adsorption adsorption ‘“~.\ M2(OH)3 4. Fe or A1 13 For Michigan soils with pH values of less than 7, most B would be in the form of H3BO3. Figure 1 shows species of B in solution at various pH values. Only above pH values of 9.2 does B(OH)Z become predominant. Soils in Michigan are usually low in extractable Al and Fe oxyhydroxides and under acid conditions small levels of B(OH)Z ions are available for adsorption. Under these conditions little or no adsorption of B was expected by the soils used in this study. Equilibrium with a solution or wastewater containing 1 mg/liter B should occur in a relatively short period of time. Total B = l mg/liter 100 -.\_ 90 1 8° ‘ H Mon); 70 . 60 1 50 . 40 . 1 30 , 20 . % Species in Solution 10 . I 0 t V U f "—V v 1 v r f V l 2 3 4 5 6 7 8 9 10 11 12 pH Figure 1.--Species of B in solution at various pH values. METHODS AND MATERIALS Leaching Experiment Undisturbed soil cores were collected from a small watershed on the site of the Water Quality Manage- ment Project at Michigan State University during the fall of 1975. The cores were taken using a Giddings hydraulic soil sampler fitted with a 6.35 cm diameter metal tube which housed an acrylic plastic sleeve. Six replicate samples of the topsoil (0-30 cm) and of the subsoil (30-60 cm) were collected for each soil type used. Three different soil series, identified at the sampling site, were used: a Lenawee loam (Mollic Haplaquept), Brookston loam (Mollic Ochraqualf), and a Metamora sandy loam (Aquic Hapludalf). Descriptions of the soils including physical and chemical properties are given in Table 1. Complete data of all the soil replicates are in Appendix I. Undisturbed cores could not be obtained from the Metamora sandy loam subsoil, and it was packed in the column by hand to approximate field bulk density. Soil from each column was removed from the top and bottom of each core to give a final soil column height of 15 cm. The soil removed from each core was used for preliminary analysis of pH, conductivity, and hot-water extractable B content. 14 215 v manmuomuuxm 04o mz i manmuomuuxm Mvm2+ mm.a «a ma vs on.o oao. moo. In ooa mm m.m m.m e Haemnsm EmoH vm.a ma ma on om.o oHo. moo. vo.a oma Hoa m.m ~.m m awowmoe apcmm muosduwz mo.a mm ma mm HH.H moo. Hmo. In Hma boa v.h m.n m Haemnsm mv.H «N on om Hm.o moo. moo. oo.H mma om v.o m.o m HMOmdoa EmoH coumxooum Ho.a me vm mm mm.o woo. ooo. In oma ow m.o m.o m Afiomnsm mm.H mm Hm cw mv.o moo. eoo. mo.~ nma oHH o.o m.m m Hwommoe EmoH mm3mcoq IImEo\mI nnnnnnnnnnnnnnnn auwlnunnnnlualalullnu Iuwuun IIAmoc83o mcoHum>uomno uwuumz «and Handthmmecfi . xwflmcmo m m m N m m wo coNfluom mmflumm Hfiom xacm wado uaflm pcmw 0 mm a 0 a4 + o Hfi oasmouo ufi>fluos©cou mm umnEzz I.“ .Haom may mo moauuwmoum Hmoaemnu can HMOHm>£mII.H wanna 16 The leaching experiment was conducted in a con— stant temperature chamber at 23°C. Leachate was applied to each column at approximately 1.27 cm/hour for four hours on two days each week. This application rate and schedule was typical of the wastewater application rate and schedule used at the Michigan State University Water Quality Management Project site. A leaching apparatus was constructed as follows. A 45 liter polyethylene carboy containing the leaching solution, which was connected to a distribution system, served as a reservoir. A tube placed through the cap of the carboy was used to maintain a constant liquid head. Teflon medical grade capillary tubing, .381 mm I.D. by 19 cm length, was used to apply the leaching solution and control flow directly onto the soil. Distribution of the leaching solution to the capillary tubes was through a 7.0 mm I.D. Tygon tube and Nalgene plastic T's. The capillary tubes were held stationary by cementing them inside a 5.0 mm I.D. acrylic plastic tubing using Sears filled epoxy resin (catalog no. 980557). A diagram of the system is shown in Figure 2 with a detailed sketch of the column in Figure 3. Preliminary trials showed that the system delivered a constant (within 10 percent) application rate over a four hour period for all columns. To improve accuracy, the effluent volumes from each column were measured after each application. 17 .ucmoammm on» uomaaoo cam mGEsHoo aflom may on coau5Hom mcflnomma on» Ho>waoc on come Emummm gnu mo Emummwo owumamsomll.~ mnemwm “1.58.. 2983.50 no 0 aaaaaaaa O at. 3.0m... 223400 a H HM a J D D p m. p $30 0 \ ‘ 02.9: zooC\ MINA 4 "722 : $0 2 : new >ommmunnm HHommou Emoa mo3mcwq on» How mm>uso amsounuxmmun mpflfionn was couomll.v madman 32.23203 53:: so :32, v m N _ o u 1 J . |J \\\\\\\\\mu\|lll.uM flung a $325 0 Km. w“. o 83.; m .\ . mum I- “a“. .\ m 4..\ . m .\. L m w. .\ . w. \ m .\LQ .mw mu .\ . N Im .. II a +1. . . m log-lollolqudlnolhflllvl.‘ I I lllllllllllllllllllll O _ A.>.m no.3 :zon. 2252235 m / L SE 2.: E8 assesses a 25 .cadaoo one ca puma coflusaom mumnomma map :a DGSOEN may Mom Umuomuuoo l .sowuwwum> mo ucmflowmmmoo ma mwmmsusmuma ca msam> + vavv o~.o Awmmv vm.o Hwomnsm EmoH Asses mm.o Iwmmo mo.o HAomdos socmm muosmumz Awovv mn.o Awamv mv.o aflomncm Ameao mm.o Awmav vm.o Hwommoa EmoH nonmxooum Ammhv Nh.o Ammeo ov.o HAOszm Ammmo ms.o +Awoao se.o HHCmdoe smoa mmsmcmq Hwom m\m on «mammam:<_aflom mammqud HMOflfimmnu mnowumwummno :0uflnom mowumm Hwom connomom m m 3552 .mHmMqud Hwom can Hmowzmmuo sown cowumHOmUm m mo mosam> nonmasoamoll.m manna 26 also generally higher in the soil method than in the graphical method (Table 2) indicating that the graphical method may be a better estimate of the amount of B adsorbed. Results of the analysis of variance of the B and Br breakthrough points, revealed significant differences between B and Br breakthrough points (Tables 3 and 4). Comparison of means of B and Br breakthrough points (Table 4) revealed that for all the soils and depths except the Metamora sandy loam topsoil, a significant difference was obtained. This supports the graphical interpretation that adsorption was observed in the soils by the difference between the B and Br curves. Table 3.--Ana1ysis of Variance of the Breakthrough Points of Br and B-—Main Effects and Interactions Calculated on the Unweighted Cell Means. Degrees of Sum of Mean F Source Freedom Squares Squares Value Breakthrough (B) 1 53.26 53.26 l42.03** Soil Series (s) 2 3.38 ' 1.69 4.51 B X S 2 4.79 2.40 6.39** Depths (D) 1 14.61 14.61 38.96** B X D 1 13.52 13.52 36.05** S x D 2 1.58 .79 2.11 Estimated error .38 ** Significant at the 1 percent level. 27 Table 4.--Mean Values of the Breakthrough Points of B and Br curves. Soil Series Lenawee Brookston Metamora loam loam sandy loam pore volumes Topsoil B 5.21a* 5.63a 3.54 .W Br 2.82b 3.32b 2.97 : Subsoil B 8.70a 11.10a 7.57a Br 2.14b 3.18b 3.04b *Different letters indicate significant differ- ences between B and Br breakthrough points within soil series and depth. LSD (.05) = 1.75. Both graphical and soil analysis supported the hypothesis that little or no adsorption of B was expected. Replications of both graphical and soil analysis were quite comparable. The coefficient of variation was highest in the subsoils, probably due to a more erratic flow pattern of the leachate moving through the heavier soil. Most of the subsoils showed slightly higher B adsorption than did the topsoils based on graphical inter- pretation, although topsoils exhibited a higher adsorption by the soil analysis. Based on the graphical data, the Lenawee loam topsoil had an average adsorption of 0.44 mg B/g of soil compared to 0.40 pg B/g for the subsoil. The Brookston loam topsoil had an average adsorption of 0.34 ug B/g, 28 and the subsoil 0.45 ug B/g. The Metamora sandy loam topsoil showed virtually no adsorption of B giving only 0.09 ug B/g of adsorbed compared to 0.24 ug B/g for the subsoil. Analysis of variance on the graphical data indicated significant differences among soil series but not depths (Table 5). There was also no significant difference between soil series and depth (Table 5). Table 5.--Analysis of Variance of Graphical Analysis Using Mean Calculated Adsorption Values. Source d.f. S.S. M.S. F Depth 2 .0088 .0044 2.68 Soil 1 .0739 .0739 45.10* Soil X Depth 2 .0117 .0056 3.41 Error 20 .0016 * Significant at the 1 percent level. Table 6.--Analysis of Variance of Soil Analysis Using Mean Calculated Adsorption Values. Source d.f. S.S. M.S. Depth 2 .0179 .0089 00.56 Soil 1 .2614 .2614 16.34* Soil X Depth 2 .0051 .0025 00.16 Error 20 .0160 * Significant at the 1 percent level. 29 Using the soil analysis, smaller differences were seen between topsoil and subsoil. The Lenawee loam showed an average adsorption of 0.75 mg B/g of soil in the topsoil and 0.72 ug B/g in the subsoil, and the Brookston loam 0.89 ug B/g and 0.73 pg B/g respectively. The Metamora sandy loam topsoil showed virtually no adsorp- tion by graphical analysis, but 0.38 pg B/g adsorbed in the topsoil by soil analysis. This value was higher than 0.26 ug B/g seen in the subsoil. This discrepancy may indicate that the hot-water extractable B value may have removed some residual soil B. Analysis of variance on the soil analysis also indicated a significant difference among soil series, but not depths or between soil series and depth (Table 6). Since both statistical analysis showed no significant differences between depths, soil property differences between the topsoil and subsoil such as organic matter, clay, aluminum and iron-oxyhydroxide content, may not be a major factor for any B adsorption found in these soils. The Lenawee and Brookston loam soil were the most similar in results. Adsorption based on both graphical and soil analysis revealed that both topsoils and sub- soils gave comparable results (Table 2). The Lenawee and Brookston loam soils were also the most similar in chemical and physical properties (Table l) of the three soil series used. The Metamora sandy loam topsoil and 30 subsoil gave lower B adsorption values in both graphical and soil analysis than the other two soil series. This soil had the lowest pH and lowest percentage of clay. Based on other studies, lower adsorption is expected since soils higher in clay content have a higher affinity for B. It was also noted that the Fe203 and A1203 con- tent was higher in the Metamora sandy loam (Table l), which further indicated the minor role these soil con- stituents may have in B adsorption by these soils at existing pH values. Soil pH and clay content were considered the main reasons for the differences seen between the soil series and apparently were the predominant factors involved with any B adsorption. The acid pH and low extractable Fe and Al content were considered the primary reasons for the limited B adsorption observed. A representative graph of extended leaching of the soil is shown in Figure 5. Boron adsorption curves of all the topsoils gave a noticeable area above the equilibrium point. This area of apparent B desorption was close to the value of adsorption in both Lenawee and Brookston loam soil series. However, soil analysis showed a net gain in soil B which contradicts this. An even larger mystery is the fact that a much greater area of desorption was noted in the Metamora sandy loam topsoil, 31 .Hfiommou Emoa mm3mcmq on» How mw>noo nmsonnvxmoun opflfioun ocm couomul.m musmflm .8533 22: kzmammm .10 m230> o. v. N. o_ o o v q] _ d A a a . . q . q A c d 9m... m1 q 822 to 8V 1 I. o 82.; m I «van ll.’ 2.50 am m3 m>too m nu as o o mu 0 .0 .m M \ V llllllllllllllllllllllllllll flfllu’b «.\..Illlll: .1 Iotltdl 0 4V. <4 or o O o . m._mN o m. o o V 32 where little or no adsorption was seen. This phenomenon was not observed in any of the subsoils. No data from the study offers any conclusive explanation for this observed effect. It may have been due to experimental error, pH changes, anion competition or compound formation of B with some other substance and a subsequent leaching out of the compound. Random experi- mental error did not appear to be the answer since reproducibility of the graphs were very good and the effect was unique for the topsoils. A pH change may have occurred where a short term alkaline state developed in the soil causing increased adsorption, followed by a quick drop to normal pH causing B desorption. The buffering capacity of the soil is usually high and this effect was not expected. Adsorption of other anions common in the soil such as Cl, P04, 804, and N03, have been found to be significantly different from B adsorption and competition or affects by these other anions was not expected (4). There are also no data offered from this study to indicate that B may have formed a new compound in the soil and was then leached out. Upon further leaching the curves did return to equilibrium. S UMMARY With little work available on B adsorption by soils in the Northeastern United States and Michigan, an experiment was designed to determine the extent to which some Michigan soils would adsorb B. Because of an increasing interest in using soil as a renovator of wastewater, the presence of B in wastewater makes it an important consideration for management of such a system. An apparatus was constructed to apply a l mg/liter B solution to undisturbed soil columns. By graphical and soil analysis the amount of B adsorbed was determined. A Lenawee loam, Brookston loam, and Metamora sandy loam soil were used. The soils were acid in pH and contained little extractable Fe and A1. Results revealed that under extended leaching, little or no adsorption of B was found among the soils, and small differences were noted between topsoil and sub- soil. Some area of desorption was seen on topsoil graphs, but no evidence was obtained by the study as to its cause. Analysis of variance and L.S.D. tests supported the graphical interpretation that differences were seen between B and Br adsorption curves except for the Metamora 33 34 sandy loam. Other statistical analysis showed a signifi- cant difference between soil series for the amount of B adsorbed. The data supports the hypothesis that little or no adsorption was expected by these soils under application of a l mg/liter B solution. This was attributed to an acid soil pH and low extractable Fe and Al. Since these soils had little retention for B, an early equilibrium state between the soil and irrigation water containing B is expected. Levels of B in the soil solution should be equal or close to those in the irrigation water. Under management of a wastewater disposal system, the use of semi-tolerant to tolerant crop species is recommended since adsorption of B was quickly established and levels of B in wastewater can be potentially toxic to plant growth. Considerations of climate, topography, soil type and crop species should be made in reference to B as a potential limitation to the use of soil in a disposal system. .1 LIST OF REFERENCES 35 LIST OF REFERENCES 1. Berger, K.C. and E. Truog. 1939. Boron determination in soils and plants. Ind. Eng. Chem., Anal. Ed. 11:540-545. from methods of Soil Analysis. Part 2, Chemical and Microbiological Properties. No. 9. Agronomy: Amer. Soc. of Agron. 1965. 1062- 1063. 2. Biggar, J.W. and M. Fireman. 1960. Boron adsorption and release by soils. Soil Sci. Soc. Amer. Proc. 24:115-120. 3. Bingham, F.T., A.L. Page, N.T. Coleman and K. Flach. 1971. Boron adsorption characteristics of selected amorphous soils from Mexico and Hawaii. Soil Sci. Soc. Amer. Proc. 35:546-550. 4. Bingham, F.T. and A.L. Page. 1971. Specific character of boron adsorption by an amorphous soil. Soil Sci. Soc. Amer. Proc. 35:892-893. 5. Bouyoucos, G.J. 1926. Estimation of the colloidal material in soils. Science 64:362. 6. Bundy, L.G. and J.M. Bremmer. 1972. A simple titri- metric method for determination of inorganic carbon in soils. Soil Sci. Soc. Amer. Proc. 36:273-275. 7. Couch, E.L. and R.E. Grim. 1968. Boron fixation by illites. Clays and Clay Min. 16:249-255. 8. Eaton, F.M. 1944. J. Agr. Res. 69. 237, taken from Sprague (37). 9. Eaton, F.M. and L.V. Wilcox. 1939. The behavior of boron in soils. USDA Tech. Bull. No. 696. December. 10. Fleet, M.E.L. 1965. Preliminary investigation into the sorption of boron by clay minerals. Clay Minerals Bull. 6, July-December:3-l6. 36 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 37 Harada, T. and M. Tamai. 1968. Some factors affecting behavior of boron in soil, I. Some soil properties affecting boron adsorption of soil. Soil Sci. and Plant Nutrit. 14:215-224. Harder, H. 1961. Incorporation of boron in detrital clay minerals explaining the boron con- tent of clay sediments. Geo-chem. Cosmochin. Acta 21:284-294. Hatcher, J.T. and C.A. Bower. 1958. Equilibria and dynamics of boron adsorbed by soils. Soil Sci. 85: 319-323. Hatcher, J.T., C.A. Bower and M. Clark. 1967. Adsorption of boron by soils as influenced by hydroxy aluminum and surface area. Soil Sci. 104:422-426. Hingston, F.J. 1963-65. Reactions between boron and clays. Aust. J. of Soil Res. l-3:83-95. Jester, W.A. and A.V. Kerry. Identification and evaluation of water tracers amenable to post- sampling neutron activation analysis. Institute for Research on Land and Water Resources, Pennsylvania State Univ. Res. Pub. No. 85. Sept. 1974. Kemp, P.H. 1956. The chemistry of borates, Part I. Borax Consolidated, London. Lindsay, W.L. 1972. Inorganic phase equilibria of micronutrients in soils. In Micronutrients in Agriculture. Soil Sci. Soc. Amer. Inc. 41-57. Mclean, E.O. 1965. Methods of soil analysis, Part 2, chemical and microbiological properties: from chapter Aluminum. Amer. Soc. of Agron:994-997. Mekra, P.O. and M.L. Jackson. 1960. Iron oxide removal from soils and clays by a dithionite- citrate system buffered with sodium carbonate. Clays and Clay Min. 7:317-327. Midgley, A.R. and D.E. Dunklee. 1939. The effect of lime on the fixation of borates in soils. Soil Sci. Soc. Amer. Proc. 4:302-307. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 38 Neary, D.G., G. Schneider and D.P. White. 1975. Boron toxicity in red pine following municipal waste water irrigation. Soil Sci. Amer. Proc. 39:981-982. Oertli, J.J. and H.C. Kohl. 1961. Some considera- tions about the tolerance of various plant species to excessive supplies of boron. Soil Sci. 92:243-247. Olson, R.V. and K.C. Berger. 1946. Boron fixation as influenced by pH, organic matter content, and other factors. Soil Sci. Soc. Amer. Proc. 11: 216-220. Okazaki, E. and T.T. Chao. 1968. Boron adsorption and desorption by some Hawaiian soils. Soil Sci. 105:255-259. Page, A.L. and F.T. Bingham. 1962. Determination of Al (III) in plant materials and soil extracts. Soil Sci. Soc. Amer. Proc. 351-354. Parks, R.Q. 1944. The fixation of added boron by Dunkirk fine sandy loam. Soil Sci. Soc. Amer. Proc. 57:405-415. Parks, R.Q. and B.T. Shaw. 1941. Possible mechanisms of boron fixation in soil. I. Chemical Soil Sci. Soc. Amer. Proc. 6:219-223. Parks, W.L. and J.L. White. 1952. Boron retention by clay and humus systems saturated with various cations. Soil Sci. Soc. Amer. Proc. 16:298-300. Pound, C.E. and R.W. Crites. Characteristics of municipal effluents. Proceedings of the joint conference on recycling municipal sludges and effluents on land, Sponsored by the Envir. Protection Agen. U.S. D.A., Nat. Assoc. of St. Univ. and Land Grant Coll. 49-59. Rajaratnam, J.A. 1972. Boron adsorption by some Malaysian soils. Mal. Agric. Res. 1:98-102. Reisenauer, H.M. and W.J. Cox. Boron uptake by plants from boron containing waters. Reprint of paper presented at 162nd Natl. American Chemical Society Meeting, Div. of Water, Air and Waste Chemistry. Sept. 12-17, 1971, Wash. D.C. p. 217; Amer. Chem. Soc. Abstract of Papers, WATR.-093. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 39 Rhoads, J.D., R.D. Ingualson and J.T. Hatcher. 1970. Adsorption of boron by ferromagnesion minerals and magnesium hydroxide. Soil Sci. Amer. Proc. 34:938-941. Sims, J.R. and F.T. Bingham. 1967. Retention of boron by layer silicates, sesquioxides, and soil materials: I. layer silicates. Soil Sci. Soc. Amer. Proc. 31:728-732. Sims, J.R. and F.T. Bingham. 1968. Retention of boron by layer silicates, sesquioxides, and soil materials: II. sesquioxides. Soil Sci. Soc. Amer. Proc. 32:364-369. Sims, J.R. and F.T. Bingham. 1968. Retention of boron by layer silicates, sesquioxides, and soil materials: III. iron and aluminum-coated layer silicates and soil materials. Soil Sci. Soc. Amer. Proc. 32:369-373. Singh, S.S. 1964. Boron adsorption equilibrium in soils. Soil Sci. 98:383-387. Snedecor, G.W. and W.G. Cochran. Statistical methods. The Iowa State University Press, Ames, Iowa, 6th edition. 1967. pp. 92-94, 460-471, 475. Spraque, R.W. 1972. The ecological significance of boron. U.S. Borax Research Co., Anaheim, Calif. Tandon, H.L.S. 1970. Fluoride extractable aluminum in soils II. As an index of phosphate retention by soils. Soil Sci. 109:13-18. Taylor, S.A. and G.L. Ashcroft. 1972. Movement of soil water. Physical Edaphology. pp. 230-234. Waggott, A. 1969. An investigation of the potential problem of increasing boron concentrations in rivers and water courses. Water Research Pergamon Press Vol. 3:749-765. Printed in Great Britan. Wilcox, L.V. 1958a. Water quality from the stand- point of irrigation. J. Am. Wat. Wks. Ass. 50, 650-654. Wilcox, L.V. and J.T. Hatcher. 1950. Coloremetric determination of boron using carmine. Analytical Chem. Vol. 22, No. 4. April:567-569. 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