Penney, D.

English

University of Saskatchewan Research Archive

213 Soil Acidity in Alberta Part l. E~tent and Importance to Crop Production Doug Penney Introduction Investigations at the Research Station Beaverlodge in the early 1960's showed that soil acidity reduced crop yields on some soils in the Peace River. region. Out o t this early work has grown a substantial research effort and a general concern for soil acidity in Alberta. Although, soils with a low pH were encountered and recognized by soil survey, their relatively high base saturation and the presence of free lime within the rooting depth of crops were cited as reasons why the acidity of these soils was of little concern to crop production. A summary by the Alberta Soil & Feed Testing Laboratory <A.S.F.T.L.) of some 80,000 farm soil samples indicates that more than 20% are pH 6.0-or less (Table l). The general distribution of these aci~ soils in the province is shown in Figure l. Assuming a reasonably uniform sampling pattern throughout the province, this indicated approximately 20% of the cultivated acreage (5 to 6 million acres) is pH 6.0 or less. An estimate of the cultivated acreage of acid soils by region is shown in Tq.ble 2. This 20% of the cultivated acreage that is pH 6.0 or less is significant from two reasons: (i) Research in other areas has clearly establishqd that alfalfa and sweet clover do not fix nitregen effic~ently when soil pH is below 6.0. Therefore, many soils in Alberta are not suited to the production of these crops. (ii) Acidification of these soils through the use of acid forming fertili-zers will result in cereal crops production being affected on a very sizeable acreage. Acidifi~ation of soils in the range of pH 6.0 or 1ess to a degree where growth of cereal crops may be effected can occur within th~ fore~eeable future. Application of 40 lbs/acre of ammonium nitrogen annually for 5 to 10 years will lower pH of many soils 0.5 FIGURE·f -~· Sc .... t -~. •o _,., "" ..... c... .. low ... [iJ ... .. s.o GJ S.l .. s.s Q] S.6 .. ... GJ ... .. ..s 8 •• .. ~ .. GJ 7.1 .. 7.J QJ 7 •• .. ••• [!] 1.1 .. I.S GJ •• .. f.D [!] ·•··· t.o 0 c.,..,.,.,., '"r "'- S.;t & ltP4 t.,,:,., teiJ,. ec •• ~., ••t ""· (! e I I I t • • • • • •• I I I I 1 t t t . ' ' .. ' . i • • • .l. •(!)•w 214 River • • l I •® I . ''' ••• ' ... .. Soil pH Mop of .. AlBERTA • • • • " II • ••• • :® (.() • •o... I I I I t I t t .......... ·········· .. ...,.. ...... ,,,,... ({) ..... ......... ,,, I S I I I I I I I I t I 11@ a Z • ,,,,,, ''"'' •••••• ::=: ·.~~~~ '¥. ·::::,·:::::: 0 It I I. I IS 5 t S 11 t I J l.t lr.l t I II ..,._ S S I I Ill I I IS I fl l 1 t $I I' I I I I U •• t I I I I I I f. I S t I t J I ft I I I I ·~ ......... , •••<D················· . . 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ISSJIJCiltl\1 1 liltS It a J I S _ t ' t \ S I t I I I It I I {!)1 I I t i C s t It 'I t t I I I t{!) I I & G),,'''''''."''''''''. ,, 'f. I I \ t l I J ' 1 ,J I I I l t I I I I ' . . .. II' It l S lll l I I I S. 1 S 1 1 I 't l ' I II '''''''''ID' ,,,, ,, • ~lit l'fiJtiJ,J•s IJI'II Ill ~llllltt•t111 7Jt 111 I ttl \!..!):;. r: : : : : : : : ; ; ~ : • ; ; : : • I : , ' ! : ! •• ~It'S 'lf.t ll' Itt tIl II I tt l '' :! ; :::!!:!!:! :'!f!cli<rltl~;-!. · ' • ., , , , , , ,. , , , ,. • • , •Ila t • • • • • , • ' ' • , ' ' ' • ' .. ' ' ' ' ' • ' , ' , c ' •• ' ' 'J ' • '~' ' " • '' ~., ''' '":;:::::::::: • !d,:(!):: ~ , l t t ' 1 t 1 • t t t t 1 , t l t t 1 1 't . t l I t ' I I t 1 ' I t I I t I l f I I 1"'1 1 I t I I ,, t' I '- l I l 1 ll I I It I I If 1 t t t l't ) t I' I I I It I It I Itt f. I I\ 1 I s I t e 1 J t 1 \ 1 t t t J. J t t t 'I t 't t t t , t t , , t t t t , I,,, c • ·-· t ' •• '. • , f "' f,' RnNGES 215 units ( 3). Table 1 Summary of pH values of farm samples analyzed by the Soil Testing Laboratory (from 1961 to 1971) . . pH Range Percent of Samples Less than 5.1 5.1 to 5.5 5.6 to 6.0 6.1 to 6.5 6.6 to 7.0 Greater than 7,0 Table 2 0.4 3.5 16.7 27.2 22.5 29.7 Amounts of cultivated farm land with soils falling Area Alberta, excluding the Peace River Region Peace River region of Alberta and British Columbia into different acid pH ranges. % of pH Range Less than 5.0 5.1 to 5.5 5.6 to 6.0 Less than 5.0 5.1 to 5,5 5.6 to 6.0 farmland 0.4 3.3 16.0 0.8 7.2 30.9 Acres of farmland 709000 660,000 3,200,000 40,000 360,000 1,545,000 About 4 percent of the samples received by the laboratory are pH 5.5 or less. Growth of such crops as barley, wheat and rapeseed can be seriously affected by acidity on these soils. Evidence from 216 some preliminary sampling in late fall of 1972 in East Central Alberta indicates that in townships where the ayerage pH is in the range 5,5 to 5.7, l/4 to l/3 of some fields have a pH of only 4.8 to 5.3. The extent and importance of this 1 type of field variation requires further investigation. Crop Response to Lime To determine the extent and degree of soil acidity damag~ to crops in Alberta, a project conducted by C.D.A., Beaverlodge and the U. of A., $oils Dep·artment was initiated in 1970, Field experiments at 30 sites from north of Ft. St. John, B.C. to Drumheller in East Central Alberta were conducted growing two varieties of barley, rapeseed, alfalfa and red clover on the soil limed to pH 6.5 and on the unlimed soil. All ~rops were grown at a high level of fertility to mask any indirect affects of liming, such as increased availability of nitrogen / or phosphorus. On the legume crops, a nitrogen and no-nitro~en treat-ment was included to separate the effect of symbiotic nitrogen ' fixation from other more direct effects of acidity. A summary of yield response to lime by crops in various pH ranges is given in tables 3,4,~, and 6. With alfalfa substantial yield increases from liming occurred even in the pH range of 5.6 to 6.0. Significant yield increases on red clover did not occur until soil pH was 5.0 or les~. (Table 3) Note, however, that the average yield of limed-alfalfa is substantially higher than unlimed red clover. Alfalfa and red clover yields were similar only on a few sites where a~ailable moisture was higher. A comparison of the effects of lime and nitrogep are given in Table 4. In 1971, 100 lbs/acre of N was applied in early spring. In 1972 the nitrogen treatments received two applications of 100 lbs/ acre; one in late fall or early spring and again after the first cut. Only 1972 yield results are shown because the 100 lbs/acre rate was found to be inadequate for two cuts. Particularly with alfalfa on soils in the pH range 5.6 to 6.0 one would expect that the main cause Table 3 Average yield &. yield increase from lime qri soils of various pH ranges Number Crop Yield (cwt per acre) Soil pH Year of Sites Alfalfa Number Red Clover and Site Years of Site No ·Lime Increase Years No Lime Increase < 5.0 1971 5 14.1 40~9 5 33.1 18.2 1972 6 15.2 44.0 6 35.0 19.3 AVERAGE ll 14.7 42.6 11 34.1 18.8 N 1-' 5.1 5.5 1971 ll 21.7 22.8 10 35.6 2.3 ....:) -1972 13 29 .• 4 17.1 ll 32.3 6.8 AVERAGE 24 25.6 20.0 21 33.9 3.8 5.6 - 6.0 1971 7 44.4 15.8 6 42.5 -l. 0 1972 6 33.8 14.1 5 34.3 1.5 AVERAGE 13 37.5 15.0 ll 38.8 0.1 6.1 1971 l 77.6 -6.8 l 73.1 19.4 1972 l 69.5 -3.1 l 62.1 2.1 AVERAGE 2 73.6 -5.0 2 69.2 10.8 Soil pH < 5.0 5.1 - 5.5 5.6 - 6.0 Year 1972 1972 1972 Table 4 A comparison df the effect of lime and nitrogen on alfalfa and red clover yields Crop Yield (cwt. per acre) No. of Sites 6 13 6 (5)* Alfalfa Lime (-N) 59.2 46.5 4B.O Red No Lime (-N) Lime C+N) 31.4 54.3 39.7 33.1 35. E 35.8 * 5 sites for ~ed clover Clover No Lime C+N) 1:\:) 1-' fXJ 35.2 27.2 30.8 219 of reduced yields would be reduced nitrogen fixation. However, even with the application of 200 lbs/acre of N, yields on the nitrogen. ' . ' . treatments were lower than on the lime treatments (35~8 cwt compare to 48.0 cwt). The reason yields on the N treatments were not similar to the lime treatment could be partially due to 'increased grass and weed competition in the nitrogen treatments. Substantial yield increases of Galt barley were obtained in the pH ranges< 5.0 and 5.1 to 5.5 (Table 5). Only moderate. yield increases occurred with Olli barley. This varietal d~fference is 6onsistent with r'sults obtained in the greenhouse. However,/becau$e of ihe large difference in yield potential of these two var~•ti~s, Olli barley produced higher Yitelds on the unlimed 'soils only in the ,'pH range <:5.0. Rape was generally affected· to a greater extent than barle~ by adverse soil and climatic conditions. As a result, rapeseed yields were more erratic. The relative yields of rapese~d an~ 0111 baFley are similar in the pH range< 5.0 (Table 6). responses of rapeseed to lime were generally ndt significant. In a greenhouse experiment conducted in 1970-71, Olii barley and :Ec~o rape.produced similar relative yields on a grey wooded sqil of pH 5.0 containing 6 ppm of 0.02M GaC1 2 soluble aluminium. Prediction of crop damage from soil acidity The cost of liming materials in Alberta i.s and will 'likely .remain ., relatively high for some time. Because of this, the need for an accurat~ nethod of predicting crop response to lime and the lime requirement of soils is particularly im~qrtant. It is w~ll established that .alumin~um and to a lesser e~tent manganese to~icity are the main causes of poor crop growth on acid soils. A relatively simple and rapid extraction method for Al and Mn using dilute CaC12 developed by Hoyt and Nyborg prdvides useful means of predict,ing crop response to lime by routine laboratory analysis. With the recent improvement in aluminium lamps both Al and Mn can be readily determined by atomic Table 5 Average yield &. yield in~rease f.r.om lime on soils o.f v.arious pH ranges ·crop Yield (cwt. per acre) Number Soil pH Year of Sit-e-s Barley and Site Galt Olli Years No Lime Increase No Lime Increase < 5.0 1971 4 16.2 15.8 2·0 .1 4.6 1972 3 17.8 11.3 17.4 4.5 AVERAGE 7 16.9 13.9 18.8 4.6 ~ ~ 11 .28. 4 4.0 24.6 1.4 0 5.1 - 5.5 1971 1972 12 25.2 5.4 22.5 2.8 AVERAGE 23 26.7 4.8 23.5 2.1 5.6 - 6.0 1971 5 39,0 1.5 27.5 1.7 1972 5 33.0 2.6 29.6 2.4 AVERAGE 10 36.9 2.1 28.5 2.1 6.1 1971 l 30.8 -2.0 23.5 -2.3 1972 1 25.8 4.1 1.0 221 Table 6 Average yield &. yield increase from lime on soils Soil pH < 5.0 AVERAGE 5.1 - 5.5 AVERAGE 5.@ - 6.0 AVERAGE Year 1971 1972 1971 19-72 1971 1972 absorption spectroscopy. of various pH ranges Span Rapeseed Crop Yield (cwt. per acre) Number of Sites and Site Years No Lime Increase 4 12.0 3.3 3 10.8 2 .. 6 7 11.5 3.0 ll 13.4 1.0 12 13.5 0.0 23 13.5 0.5 5 16.8 0.4 5 17.0 2.2 10 16.9 1.3 The scatter diagrams (Figures 2, 3 and 4) show the type of relation-ships obtained between CaC1 2 - soluble Al, pH and the yield of barley, red clover and alfalfa. A comparison of the simple correlation coefficients (r) obtained with soluble aluminium and pH are showing in Table 7. Soluble aluminium was better than pH for predicting crop response to lime on barley, rapeseed and red clover. For alfalfa pH in water was better than soluble A1. This would be expected because alfalfa yields are re)duced substantially in the pH range 5 .. 5 to 6. 0 where little or no soluble Al is present. The inclusion of Mn with Al in a regression analysis generally did not improve the prediction of crop response to lime. v,ry few of the sites had soluble Mn levels in FIGURE 2 ·.- YIELD CURVE FOR GALT BARLEY VS. 0.02M CACL2 Al 1/0 mo~~--------------------------------------------~6b w 80 ""="" ..... _ .......... _J w f- 0::: ::::> u C> <r: ::r::: 10 'f& ;;, f-.......... _J t-J ::;:: w t-J • ::r: t-J 0 (/) _J ::::> U,..J 60 'fOc:Q ->-~ • 50 • 33 0 I 2 3 'f 6 7 8 SOLUBLE AL (PPM) FIGURE 3- YIELD CURVE FOR RED CLOVER VS. 0.02M CACL2 AL :1~ ........ :·_________________ ........_ __________ --r .:~ 2.3 w ~ -......J I-=> 0 ::c 1--3: t:::l . I) ~ \ . iO e\ 80 7o •• i:jj·· 'fO ->-~ 3 20 10 0 • • • • . 12 /3 2l /.8 LJ..I j.{, 5 < ......._ >-/.Jf ~ (/) --...... __ /.} C> ..__ ---0.9 Q. _J Lt.J -0-7 >-0.5 o.z 0 30 36 if2 fS SOLUBLE AL (PPM) I)) I)) (.o) FIGURE 4- YIELD CURVE FOR ALFALFA ON GRAY WOODED SOILS VS. PH 1/0 • Joo 3.0 90 2.7 • 30 Z.'f • 1..1.1 a:: 70 2./ u < w ' !E >--....J 1.8 <C ::c t- (I) => -.... -0 :r: 1-....... :::: /.5 ~ 2: tr) -tr) .. :J /.Z 9 w 1..1.1 - ->- >-~ 0/1 Q./, 0.3 0+-------------~~--~----~--------~·~--~----+ o.o . 6.2 6.0 5.8 5.2 5.0 f.8 'f.Jf SOIL PH 225 the range considered to be toxic. Table 7 Simple correlation coefficient (r) of percent yield without lime ys. pH (water) and 0,02M CaCl 2 soluble aluminium , (two years data- 1971 and 197·2) Crop Red Clover Alfalfa Galt barley No. Of· Sites 24 26 25 * Log transformation 10 ' pH 0.67 0.79 0.66 Correlation Coefficient (r) Al -0.91 -0.66 (-0.78)* -0.85 Future Research on Soil Acidity The bulk of the yield data obtained to date were obtained under conditions of relatively high rates of fertilization and comparing crop growth on the unlime~ soil and on the soil limed to near neutrality. Several workers haye suggested that maximum crop yields can be obtained with adequate fertilization and liming to reduce Al and Mn below toxic levels (to a pH of about 5.5). Investigations of fe:rtiliz~ - lime interactions are needed to determine the lowest cost combination. Developmerit of a reliable and relatively rapid lime :requirement method is needed. Methods developed to date provide a lime requir~ment to bring ~oils to a pH near neutrality. Methods for predicting the lime requirement to reduce Al and Mn below toxic levels require further study. In some casesp a suitable alternative to liming acid soils is growing acid tolerant crops. This may be particularly important where the cost of lime is high. A complete inventory of the acid tolerance 226 of commonly grown species and varities is needed. Some of this work has been don~ and is going on. I Summaries of soil test data have provided a good basis for assessing the extent of soil acidity problems. To some extent 9 further delineation of acid soil problems by sampling surv~ys of problem areas I is needed. In areas where summaries show average pH in the moderately acid range, further sampling is needed tQ determine the amount of field variation and an estimate of the acreage of strongly acid soils. Summary l. Soil acidity is and will become an increasingly important factor in crop production in Alb~rta. ) of lime is evident. The need £or an economical source 2. The development of methods suitabl~ for routine determination of Al and Mn provide a good basis for predicting crop response to This in conjunction with a reliable lime requirement test will provide a basis for farmers to asseas the economics of various management alternatives on acid soils (i.e. - liming and/or growing acid tolerant crops). References 1. Adams, F. and R. W. Pearson. (ed.) 1967. Soil acidity and liming. Monograph 12, Amer. Soc. Agron., Madison, Wis. 2. Hoyt, P. B. and M. Nyborg. 1971. Toxic metals in acid soils: I. 3 . 4. 5 0 Estimation of plant-available aluminium. II. Estimation of plant-available manganese. Soil Sci. Soc. Amer. Proc. 35:237-24~. Hoyt, P. B. and M. Nyborg. communication. Unpublished results - personal Kamprath, E. J. 1970. liming leached mineral 34:252-254. Exchangeable aluminium as a criteria for soils. Soil Sci. Soc. Amer. Proc. Penney, D. C. 1973. Unpublished M. Sci. thesis. 

Soil acidity in Alberta – Part I: extent and importance to crop production

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Soil acidity in Alberta – Part I: extent and importance to crop production

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