AGRONOMIJAS VÄSTIS - Latvijas LauksaimniecÄ«bas universitÄte

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<strong>AGRONOMIJAS</strong> VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008IMPACT OF ANTHROPOGENIC FACTORS ON THE CHANGE OF LIMED SOILPROPERTIESKoncius D.Lithuanian Institute of Agriculture, Vezaiciai Branch, Gargzdu 29, Klaip÷da distr., Lithuania, LT-96216, phone: +370 46 458233, e–mail: kodo@vezaiciai.lzi.ltAbstractField and laboratory trials were carried out in the Vezaiciai Branch of the LithuanianInstitute of Agriculture in 1977-2005. The soil of the trial site was the Bathihypogleyi - DystricAlbeluvisol (ABd-gld), texture - morain loam. To evaluate the effect of various combination ofliming and fertilization on the change of soil chemical properties was the aim of this investigation.The planned pH levels (factor A) - pH 6.7were establihed by primary liming with pulverized limestone in 1976. Pulverized limestone (92.55% CaCO 3 ) rates were as follows: 1.9; 3.3; 5.8; 14.7 and 49.6 t ha -1 respectively.The object of the investigations was naturally acid soil and the same soil exposed to a longterm(more than 29 years) anthropogenic load. The essential and lasting (r = 0.8–0.9) variation ofmorain loam soil pH KCl under different anthropogenic load were established. The acidificationprocess had a negative effect on the soil chemical properties. The highest variation of the topsoilpH KCl index to its diminishing (from 6.7 to 4.0) was obtained in the soil annually fertilized with aN 135 P 117 K 171 rate of mineral fertilizers.It was revealed that the soil acidification process under the effect of intensive mineralfertilization (in both backgrounds with and without manure) was more intensive than in thenonfertilized soil. Systematic long-term manuring had a positive effect on the soil chemical state:decreased the soil acidification process and suspended the increase of mobile aluminium amounts.Key wordsSoil acidification, primary liming, mineral and organic fertilization, pH.IntroductionMost of Lithuanian albeluvisols and luvisols are acid by nature. The experimental evidenceobtained in Lithuania and other countries suggests that the major means for taming these soils areliming, organic and mineral fertilisation (Plesevicius, 1995; Conyers et al., 2003). Liming of acidsoils resulted in significant changes in soil properties. Natural soil forming (pedogenic) processesare continuously occurring in nature, one of which is soil acidification. This process is promoted inagrosystems by abiotic and anthropogenic factors: acid precipitation, crop and soil managementpractices, application of physiologically acid mineral fertilisers, Ca, Mg and other elementsleaching and removal with yield (Ciuberkien÷ et al., 2000). The level of soil acidification dependsmainly on the mother rock, climate and biocenose (Kaczor, 2002). This all results in a continualsoil chemical and biological degradation (Douglas, 2000). Acidification rates of these naturallyacid and acidifying soils that formed in different territories are significantly increased byanthropogenic activity. The acidification resulting from this activity is to the greatest extentaffected by intensive mineral and organic fertilisation, soil tillage and pesticide use (Malhi et al.,1998; Ciuberkiene et al., 2000; Barak 2000; Conyers et al., 2003). Rapid soil acidification afterliming is determined by the removal of alkaline compounds (base cations Ca +2 , Mg +2 ) from theecosystem with plant production, nitrification caused by excess of ammonia nitrogen sources andthe accumulation of hydro carbonates, nitrates, chlorides, sulphides, and other soluble salts andNH + ; H + ions in the soil. The increasing soil acidification rate is also considerably affected by theexcess of organic acids in the soil which occurs due to intensive organic matter accumulation(Helyar, 1991).The western zone of Lithuania receives a large annual amount of precipitation of 800-850mm (the national mean is 675 mm). As a result, the area of acid soils is increasing steadily, sincetopsoil loses 120–200 kg ha -1 of calcium annually (Mazvila et al., 2000). Soil liming not only42
<strong>AGRONOMIJAS</strong> VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008neutralises mobile aluminium, which is one of the most toxic elements for plants, but also causeschanges in agrochemical properties, nutrient content and uptake, humus qualitative composition(Svedas, 2000). Summarising the literature data we can affirm that the soil acidification ratedepends on the nature of the anthropogenic load and the geochemical state of the soil.The aim of the research was to evaluate the effect of various combinations of liming andfertilization on the change of soil chemical properties.Materials and MethodsThe long-term trial was established at the Lithuanian Institute of Agriculture VezaiciaiBranch (55 o 41‘N, 21 o 30‘E). The experiment was conducted on the the Bathihypogleyi - DystricAlbeluvisol (ABd-gld), texture - morain loam.. The topsoil before experiment arrangement wasvery acid pH KCl 4.3–4.4, hydrolytic acidity – 42–51 meq kg –1 , base saturation level – 23–26 %,mobile aluminium – 42-70 mg kg –1 soil. The soil was low in phosphorus and high in potassium – 72–99 and 232–264 mg kg –1 soil, respectively, humus content about 2 %. The planned pH levels (factorA) - < 4,7 (unlimed), 4.7–5.2; 5.2–5.7; 5.7–6.2; 6.2–6.7 and > 6.7 were established by primaryliming with pulverized limestone in 1976. Pulverized limestone rates were as follows: 1,9; 3,3; 5,8;14,7 and 49,6 t ha -1 respectively.The five course crop rotation was as follows: 1) spring rape cv. ‘Sponsor‘ (Brassica napusannua L.), 2) spring barley cv.‘Ula‘ (Hordeum vulgare L.), 3) red clover cv.‘Liepsna‘ Trifoliumpratense L .) and timothy grass cv. ‘Gintaras II‘ (Phleum pratense L.), 4) winter wheatcv.‘Sirvinta‘ (Triticum aestivum Host.), 5) oats cv.‘Selma’ (Avena savita L.). Mineral fertilizers –ammonium nitrate (NH 4 NO 3 ), superphosphate (Ca(H 2 PO 4 ) 2 +2CaSO 4 ) and potassium chloride(KCl) in the experimental plots were used according to the following scheme (factor B): withoutfertilizers, single, double and triple rates of NPK. Single mineral fertiliser rate (N, P 2 O 5 , K 2 O or NPKfor short) for spring rape was N 70 P 60 K 90 , for spring barley and winter wheat – N 45 P 30 K 45 , forperennial grasses first usage year – P 45 K 60 . Plot size was as follows: 80 m 2 (brutto) and 48 m 2(netto). The treatments were replicated threefold. Randomised design was used.The soil samples for chemical analyses were taken from every plot annually afterharvesting. from the topsoil (0-20cm). Chemical analyses of soil samples were done using thefollowing methods: pH KCl potentiometrically (ISO 10390:2005), exchangeable (mobile) Al – by theSokolov method. Experimental findings were processed using correlation–regression analyses.Results and DiscussionThe object of the investigation was naturally acid soil and the same soil exposed to a longterm(more than 29 years) anthropogenic load. The essential and lasting (r = 0.8–0.9) variation ofmorain loam soil pH KCl under different anthropogenic loads was established. The acidificationprocess had a negative effect on the soil chemical properties. The highest variation of the topsoilpH KCl index to its diminishing (from 6.7 to 4.0) was obtained in the soil annually fertilized with aN 135 P 117 K 171 rate of mineral fertilizers. Primary liming with high chemically active lime rates hadthe greatest effect on reducing soil acidity. Unlimed and limed soil under natural conditions an 0,2pH unit acid level in 29 years (figure 1). The rate of soil pH variation of limed soil was highlydependent on the rate of initial liming (figures 1, 2). Acidification in soil limed to pH 5,2-5,7 wasmore rapid (-0,9 pH unit) and in 29 years pH reached the initial measurments, i.e. soil became veryacidic. More intensive acidification was determined when soil was limed to pH 6,2-6,7. Here pHdecreased by 1,3 unit after liming, however after 29 years it was about 0,3 unit higher than beforeliming.Mineral fertilizers increased soil acidification, especially when fertilizing with high rates(N 135 P 117 K 171 ) pH changes were diverse in different pH soils. When the soil was very acidic (pH4,4-4,6) small mineral fertilizer rates decreased pH by 0,2 and high rates (N 135 P 117 K 171 ) – by 0,7units.Acidification in slightly acid soil was more intensive, however the influence of mineralfertilizers was less even when under high rates of fertilization. Mineral fertilizers influence onacidification processes in limed to pH 6,2-6,7 level soil was similar to very acidic soil. Fertilizingwith N 45 P 39 K 57 rate decreased pH by 0,2 and fertilizing with N 135 P 117 K 171 – by 1,1 units.43
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