soil distribution and soil properties in the subalpine region of kazbegi greater caucasus georgia soil quality rating of agricultural soils

Accepted Manuscript Soil distribution and soil properties in the subalpine region of Kazbegi; greater Caucasus; Georgia: Soil quality rating of agricultural soils Thomas Hanauer, Carolin Pohlenz, Besik Kalandadze, Tengiz Urushadze, Peter Felix-Henningsen PII: S1512-1887(16)30073-2 DOI: 10.1016/j.aasci.2016.12.001 Reference: AASCI 76 To appear in: Annals of Agrarian Sciences Received Date: October 2016 Revised Date: December 2016 Accepted Date: 16 December 2016 Please cite this article as: T Hanauer, C Pohlenz, B Kalandadze, T Urushadze, P Felix-Henningsen, Soil distribution and soil properties in the subalpine region of Kazbegi; greater Caucasus; Georgia: Soil quality rating of agricultural soils, Annals of Agrarian Sciences (2017), doi: 10.1016/j.aasci.2016.12.001 This is a PDF file of an unedited manuscript that has been accepted for publication As a service to our customers we are providing this early version of the manuscript The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain ACCEPTED MANUSCRIPT Soil quality assessment SOIL DISTRIBUTION AND SOIL PROPERTIES IN THE SUBALPINE REGION OF KAZBEGI; GREATER CAUCASUS; GEORGIA: SOIL QUALITY RATING OF AGRICULTURAL SOILS RI PT Surnames, first names and patronymics of the authors Hanauer, Thomas*; Pohlenz, Carolin*; Kalandadze, Besik**; Urushadze, Tengiz***; Felix-Henningsen, Peter** 10 SC Name of the institution, address, positions and scientific degrees of the authors 11 *Justus Liebig University Giessen, Institute of Soil Science and Soil Conservation 13 Heinrich-Buff-Ring 26-32, Giessen, 35392, Germany; thomas.hanauer@umwelt.uni-giessen.de: M.Sc / Dr / 14 Prof Dr 15 **Ivane Javakhishvili Tbilisi State University, Department of Geography 16 1, Chavchavadze ave., Tbilisi, 0179, Georgia; kalandabeso@gmail.com: Prof Dr 17 ***Mikheil Sabashvili Institute of Soil Science, Agrochemistry and Melioration, Agricultural University of 18 Georgia, 13 km, David Agmashenebeli Ave., 0159, Tbilisi; t_urushadze@yahoo.com: Prof Dr AC C EP TE D M AN U 12 ACCEPTED MANUSCRIPT Soil quality assessment SOIL DISTRIBUTION AND SOIL PROPERTIES IN THE SUBALPINE REGION OF KAZBEGI; GREATER CAUCASUS; GEORGIA: SOIL QUALITY RATING OF AGRICULTURAL SOILS RI PT Keywords: Muencheberg Soil Quality Rating; Alpine Soils; Cambisols (Humic); Cambic Umbrisols; Kazbegi 10 SC ABSTRACT 12 Soils of the alpine ecosystem of Kazbegi region were investigated according to the Muencheberg Soil Quality 13 Rating (M-SQR) Most limiting factors are climate as well as steepness, while the low nutrient supply and soil 14 acidity can be tackled by adequate fertilization and liming practice Inorganic or organic pollutions were not 15 detected Soils on sediment fans as well as glacial sediments, mostly Cambisols (Humic), are characterized by a 16 low to moderate yield potential while high-yield soils, mostly Cambic Umbrisols, can be found on volcanic 17 plateaus A common element of all soils is the high humus content Actually, most of them are used only for 18 pasture, due to poor accessibility Soils on fluvial deposits, mostly Fluvisols, show a very high range of M-SQR- 19 scores Altogether, the soils of the study area have the actually untapped potential to optimize the basic supply of 20 the local population as well as tourism also by cultivation of cereals Nevertheless, variety trials on different soil 21 forming substrates as well as erosion control are major preconditions for successful implementation of new 22 cropping systems in the Kazbegi region Furthermore, particularly rare soils, e.g Cambisols on Tephra, should 23 be protected 25 TE D EP AC C 24 M AN U 11 INTRODUCTION 26 Soil quality is, beside climate, the fundamental requirement for prosperity and development of a rural 27 population Therefore, assessment of soil quality, yield potential and soil ecological functions are essential parts 28 of the interdisciplinary AMIES II‐project, which aims to support the rural development of the Kazbegi district in 29 the Greater Caucasus It focuses on the human‐environment interface and comprises ecological and socio‐ 30 economic research to develop sustainable, agricultural land‐use options 31 Due to the Soil Science Society of America (SSSA) soil quality is defined as: ‘the capacity of a specific kind of 32 soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, 33 maintain or enhance water and air quality, and support human health and habitation’ [1] In the frame of the 34 project the Muencheberg Soil Quality Rating (M-SQR) for crop and farmland as well as grassland designed by ACCEPTED MANUSCRIPT 35 [2], valid for a wide range of soils, was applied in the mountainous area of Kazbegi to evaluate the potential of 36 agricultural soils of the area on an international basis The M-SQR was chosen for this purpose, due to its 37 concept to ‘measure long-term soil quality and estimate of the local crop potential’, its suitability for grassland as 38 well as arable land and especially due to its internationality, because of using the FAO Guidelines for soil 39 description [2] This article summarizes the results of field campaigns in 2014 and 2015 41 STATE OF KNOWLEDGE RI PT 40 Due to increasing pressure on existing and potential agricultural land a multitude of approaches exist to quantify 43 agricultural soil quality resp the production function However, due to differing input data ratings are not 44 transferable or universally applicable [3] Soil rating focuses on the evaluation of soil fertility, e.g yield potential 45 of arable soils [4] Due to Müller et al [27] three natural limits to growth can be distinguished (1) temperature 46 and moisture regime of the soil, (2) internal soil deficits, e.g a substrate hindering root growth and nutrition 47 supply, and (3) the relief A brief summary of the different approaches has to start with the Californian Storie- 48 Index Rating (SIR), evaluating soil type, texture and further parameters (nutrients, erosion etc.) and developed 49 already in 1933 It is a multiplicative and parametric System, multiplying percentage performance levels (x:100) 50 to get the final so called Storie-Index [4] [5] The FAO developed rating systems, too At first the Land 51 Suitability Classification (LSC), developed in 1960 and focusing on natural conditions limiting the yield 52 potential: Thermal and moisture regime, nutrient supply and relief as well as socioeconomic factors of the site 53 Hence, more emphasis is on rating of climatic and edaphic factors then soil rating itself In a second project, the 54 ‘Agro Ecological Zones’, agro-climatic zones were combined with the already existing Soil Map of The World 55 (1:5.000.000) to get suitability classes for different crops [4] Furthermore, national soil ratings exist like the 56 German ‘Amtliche Bodenschätzung’, rating the natural yield potential by soil properties, relief, climatic 57 conditions and moisture regime [6] From its basic it is a fiscal instrument but often used for agro-ecological 58 issues, actually To get an international consistent rating scheme the Soil Quality Assessment was developed in 59 the USA It focuses on small data sets of the evaluated soils to determine soil quality by only a few 60 measurements [7] A method explicitly accounting for the soil productivity of arable land as well as grassland is 61 the Muencheberg Soil Quality Rating (M-SQR) [2] For example, M-SQR was already applied extensively in 62 Germany, based on soil maps (1:100.000) [8] Furthermore, the practicability and reliability was confirmed by 63 field tests in several countries and the rating scores are well correlated with crop yields, especially at a moderate 64 level of farming intensity [3], as it is typical for the study area The results of the M-SQR and the soil properties 65 primarily concerning the yield potential are discussed here By means of this rating, the arable productivity can 66 be estimated on a global scale [8] Hence, M-SQR was chosen for the purpose of this article AC C EP TE D M AN U SC 42 67 68 69 3.1 Location and climate STUDY AREA ACCEPTED MANUSCRIPT The Kazbegi study area is located in the Mtskheta‐Mtianeti region and aprox 155 km2 in size (aprox 270 are 71 settlements) The Kazbegi district (population approx 6,500) as an administrative unit stretches from the 72 dividing Jvari Pass (‘Cross Pass’) to the Russian border (North‐Ossetia and Ingushetia) on the northern slope of 73 the Great Caucasian Ridge It is characterized by the valley of the Tergi (Terek) river and the Georgian Military 74 Highway, one of the major routes crossing the Caucasus (Fig 1) The main town Stepantsminda (‘Kazbegi’ in 75 Russian, 1,850 m a.s.l.; population 1,700) is characterized by a moderately humid climate with relatively dry, 76 cold winters and long, cool summers The average annual temperature is 4.9 °C January is the coldest month 77 with an average temperature of ‐5.2 °C, while the maximum average temperature is 14.4 °C in July [9] Besides 78 Stepantsminda, the region is sparsely populated AC C EP TE D M AN U SC RI PT 70 79 80 Fig Location of the study area in N Georgia according to [10] (modified); total size of study area: 81 154.94 km2 82 3.2 Soil resources of the study area ACCEPTED MANUSCRIPT Elevation of the study area is restricted to the montane to alpine zone [11] The landscape morphology is diverse 84 and shaped by quaternary fluvial and glacial sediments, Tertiary and Quaternary volcanic rocks and Jurassic 85 sedimentary rocks [12][13][14][15] The study area belongs to the geomorphological zone of the Tergi-Arguni 86 interridge isoclinal depression (Kazbegi-Khevi intermontane basin) [16] and is characterized by high tectonic 87 and geomorphologic activities The Kazbek Neovolcanic center was still active in late Quaternary until less than 88 50 k y BP The last satellite volcano Tkasrsheti erupted in middle Holocene, approx k y BP The 89 stratovolcano Kazbek became a center of eruption with lava flows extended up to 15 km Its lavas have a mixed 90 mantle-crustal origin composition of mainly porphyry, rarely aphyric, rocks varies from basaltic andesites 91 (basaltic trachyandesites) to dacites with a leading role of dacite lavas [17] Three small explosive apparatuses 92 are localized in the study area: near Pkhelshe, downward Sioni and at the mouth of the Chkheri River [17] NE’ 93 Stepantsminda 94 The second important bedrocks are flysch terrigenous and carbonate sediments of the complete Jurassic [16] 95 (primary clay slates but also marlstone) and lower Cretaceous (limestone) [12][13][14][15] The quaternary 96 fluvial and glacial deposits are composed of both of these bedrocks Due to this, a sediment cascade typical for 97 the alpine geosystems [18] can be found in the study area: rock face, valley head (regolith), slope (debris/ talus 98 fan), valley plain (alluvial sediments, terraces) Pediments are formed by sediment fans (e.g talus) of Jurassic 99 sediments or by slope loam and debris of volcanic rocks M AN U SC RI PT 83 Mudflows are a common natural hazard in Georgia (about 37 occurrences in the past 200 years), mainly due to 101 intensive precipitation and consequent flooding with hot spots e.g in the Tergi river basin [19] However, due to 102 [19] the study area is only in a zone of medium landslide hazard level Furthermore, >70% of the territory of the 103 Tergi river basin is subject to avalanches [20] 104 Dominating soil types are Leptosols, Cambisols, Gelysols and Histosols [21] Due to Urushadze [22] Mountain- 105 Meadow soil (Leptosols) are spread in the study area (1,800 to 3,200 m a.s.l.), bordered by Leptosols (upper 106 zone) and Cambisols (lower zone) These soils are characterized amongst others by acid and weakly acid 107 reaction, a high content of humus as well as deep humus penetration [22] As the study area is situated in the 108 hypsometric level for (peri)glacial processes of the middle belt e.g alpine to subalpine landscape (1,750 – 2,300 109 m a.s.l.), slope (solifluction, rock-streams, snow avalanches, talus trains and mudflows) as well as plane 110 (polygonal-structural) processes of periglacial morphogenesis prevail [20] The soil-climatic conditions in the 111 study area are characterized by a soil temperature at surface resp at 20 cm depth of 4.5 Furthermore, phosphorus availability might be limited (referring to SQR-hazard indicator ‘low total 306 nutrient status’) if the soils show protoandic properties Error! Reference source not found These result in an 307 increased phosphate-fixation by allophanes and metal-humus complexes, due to a high anion exchange capacity 308 This could also be a problem for other anionic nutrients (e.g nitrate or chloride) [31] In Table the 309 phosphorus-retention of three different soils is shown A Cambic Umbrisol (Protoandic) (P07) has developed on 310 slope loam over Andesite-Dacite (close to Ukhati), while a Cambisol (Humic Tephric) (P16) has developed 311 directly on significantly younger (very likely from Holocene) and only weakly weathered tephra (close to Sioni) 312 In contrasts, A Cambisol (Humic) (P11) has developed on debris of clay slate (above Stepantsmida) P07 shows 313 a dramatically higher phosphorus-retention than P16 due to the formation of Fe- and Al-oxides in the Umbrisol 314 of P07 by weathering of silicates, with a significant proportion of allophanes and ferrihydrite (see Tab 2: 315 Alox+1/2 Feox), certainly Hence, cropping may need an increased phosphorus-fertilization combined with liming 316 to increase soil-pH and to decrease anion exchange capacity 317 Table 2: P-sorption of two soils on volcanic influenced unconsolidated rock (P07, P16) and one on debris of 318 Jurassic sedimentary rocks; Alox+1/2 Feox [mg kg-1] = active oxides [44], diagnostic criteria due to Error! 319 Reference source not found M AN U SC RI PT 302 Added P [mg l-1) Sorbet P [%] Alox+1/2 Feox [mg kg-1] P07 / Ah2 (Cambic Umbrisol 25 100 250 25 100 93 61 100 10.306 Protoandic) P07 / Bw-Ah AC C P16 / Bw P11 / Ah (Cambisol Humic Tephric) P11 / Bw 100 250 25 100 150 25 95 64 17 28 100 150 25 100 150 25 100 150 11 76 37 27 68 35 22 EP P16 / Ah (Cambisol Humic) TE D Profile/horizon 12.815 5.335 4.710 1.087 1.599 320 321 Within the Pleistocene major parts of the study area were covered by glaciers, as it is easy to conclude from the 322 shape of valleys and the distribution of end and side moraines, e.g in the Truso valley Hence, soils developed 323 on glacial deposits partly covered by Holocene deposits For example in the Chkheri valley, WNW’ ACCEPTED MANUSCRIPT 324 Stepantsminda, a groundmoraine is buried beneath late-glacial fluvial sediments or at the Ukhati plateau by 325 colluvium (P05, P36; see Fig 6) Hence, only a total area of 398 ha, or less than 3% of the study area, various 326 glacial sediments are the parent material of the complete soil However, in other soils they participate as layers in 327 deeper parts A typical hazard indicator for these soils, mostly Cambisols or Umbrisols but also Calcaric 328 Regosols, is a ‘high percentage of coarse soil texture fragments’ due to bed load of the moraines M AN U SC RI PT 329 330 Fig Cambic Umbrisol (Hyperhumic) (P23 N’ Juta, see Fig 6) as a typical soil on an endmoraine, with a high 332 content of organic matter and fine earth, but rather shallow Land use 2015: pasture; M-SQR rating 40 points 333 (class: poor) 334 Fluvisols or soils with fluvic properties cover 2.081 or ca 13% of the study area These soils are formed on a 335 variety of substrates, depending on source area of the watercourse as well as distance to the water divide Due to 336 dominating calcareous sedimentary rocks in the south of the study area, most alluvial sediments are calcareous 337 Water logging and ponding up to paludification is a problem in case of the braided river beds of the Truso river 338 (below Ukhati) and the Snotskali river (SE Akhothi), resulting in the SQR-hazard indicator ‘flooding and 339 extreme waterlogging’ However, the main hazard indicator ‘high percentage of coarse soil texture fragments’ is AC C EP TE D 331 ACCEPTED MANUSCRIPT a result of postglacial outwash as well as mass movements on slopes in the study area, especially at the low 341 terraces 342 Fig Depending on the substrate yield potentials of the Fluvisols differ within a broad range: a) Calcaric Gleyic 343 Fluvisol (P03, see Fig 6), on haugh, Truso valley, SQR rating 50 points (class: moderate); b) Calcaric Skeletic 344 Regosol (Humic Fluvic) (P29, see Fig 6), on coarse gravel and rubble, pasture; NE’ Achkhoti, SQR rating 34 345 points (class: poor) 346 Histosols occur in isolated and small areas in abandoned braided river beds, e.g between Achkhoti and Sno (ca 347 in size, see Fig 6), or slope flattenings above an aquiclude, e.g at the counter slope S’ Ukhati (see Fig 6) 348 Bogs are not taken into account of the SQR-map due to the small size of the areas Generally, similar restrictions 349 for cultivation apply as in case of the Fluvisols with an extreme water regime as mentioned above For example 350 the drained low-level moor between Achkhoti and Sno is used as a meadow in 2015 AC C EP TE D M AN U SC RI PT 340 M AN U SC RI PT ACCEPTED MANUSCRIPT 351 352 Fig Map of the SQR-Score [2] of the study area, in case of the Jutistkali River no fluvial parent material is 353 shown separately, due to dominating slope processes in the steep gorge 355 TE D 354 5.3 Hazard indicator ‘contamination’ [28]: Due to the aim of the study to supply information for a sustainable agricultural and horticultural land use 357 particular care has been given to the hazard indicator ‘contamination’ For this purpose trace metals as well as 358 organic pollutants/chemicals were measured in selected samples 359 Trace metals increase in soils on bedrocks containing high lithogenic amounts This is the case for sedimentary 360 resp metamorphic as well as volcanic rocks [46]; both are more or less sources of all soil forming substrates in 361 the study area The andesite and dacite lavas of the Kazbek nevolcanic center show e.g Ni and Cr concentrations 362 of 15-150 resp 30-270 [mg kg-1] [17] 363 In Table 3, selected trace metals in the topsoil horizons of the soil explorations as well as further sampling 364 points are shown In a few case total concentrations exceed Georgian thresholds [47] However, mobile forms 365 are relevant for risk assessment Due to this 10 % of the samples, covering the range of metal concentrations, 366 were extracted with M NH4NO3-solution to evaluate mobile species As expected, only a very small part of 367 total concentrations belongs to the mobile fraction Hence, elevated trace metal concentrations can be traced 368 back to lithogenic background concentrations which cause only a very small risk for a translocation into food 369 chain 370 Table 3: Selected trace metals in the Ah horizons of soils of the Kazbegi region AC C EP 356 ACCEPTED MANUSCRIPT Trace Metal Min Max [mg kg-1] Arithmetic mean, Median standard deviation1 Georgian N Mobil form2 threshold (clay, pH