Carbon Losses and Soil Property Changes in Ferralic Nitisols from Cuba Under Different Coverages
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311 Scientia Agricola http://dx.doi.org/10.1590/1678-992X-2016-0117 Carbon losses and soil property changes in ferralic Nitisols from Cuba under different coverages Alberto Hernández-Jiménez1, Dania Vargas-Blandino1, José Irán Bojórquez-Serrano2, Juan Diego García-Paredes2*, Alberto Madueño-Molina2, Marisol Morales-Díaz3 1National Institute of Agricultural Sciences, P.O. Box 32700 ABSTRACT: The transformation of primary forestlands into lands under cultivation exerts an − San José de las Lajas, Mayabeque − Cuba. impact on the physical and chemical properties of the soils, leading to loss of carbon from 2Autonomous University of Nayarit/Academic Unit of the soil. The aims of this study were (1) to estimate the impact of different land use on organic Agriculture, km 9 Carretera Tepic − 63000 − Compostela, carbon stock (OC-stock) and (2) to determine the clay percentage, the dispersion factor, and Nayarit − Mexico. bulk density with regard to soil management. Thirty soil profiles were sampled as follows: four 3Institute for Fundamental Researches on Tropical under primary forests with 80-100 years (old growth); two under secondary wood forests with Agriculture, Calles 1 y 2, P.O. Box 17200 − Santiago de las 45-50 years; eight under secondary young forests with 15-25 years; four under pasture land with Vegas, Havana − Cuba. 15-20 years; and 12 under continuous cultivation for > 50 years. We determined the changes in *Corresponding author <[email protected]> OC-stock in the soils under different land-use conditions in relation to the primary forest variant. There was a difference in the OC-stock of the continuous cultivation variant compared to the Edited by: Carlos Eduardo Pellegrino Cerri remaining land-use variants for all soil-thickness layers. The greatest loss of cultivated soil was in the 0-20 cm layer of the primary forest OC-stock. In the 50-100 cm layer, the OC-stock of the cul- tivated soils diminished significantly. As regards physical properties, such as clay percentage,, dispersion factor, and bulk density, we observed significant differences between the cultivated Received March 17, 2016 soils compared to the remaining land-use variants. Accepted August 03, 2016 Keywords: degradation, carbon reserves, physical properties, tropical soils Introduction (SOC) distribution, storage and loss in the surface and subsurface soil horizons. Other factors that affect the dy- The transformation of primary forest land into namics of SOC are land use, climate, and soil landscape land under cultivation exerts an impact on the physical processes (Olson et al., 2011, 2012). One essential point and chemical properties of soil, leading to loss of carbon to consider is the depth at which soil samples are taken from the soil and its emission into the atmosphere in since the interaction between the root system and the the form of CO2, which enriches the greenhouse-effect soil profile has an influence on soil carbon accumulation gases that are currently ushering in climate change (Don (Olson and Al-Kaisi, 2015). Also, organo-mineral interac- et al., 2011; Xiong et al., 2014). There are estimates that tions are an important factor in SOC storage (Grand and the conversion of natural ecosystems into agrosystems Lavkulich, 2011). Soil texture affects carbon retention is responsible for approximately 24 % of worldwide CO2 capacity, and fine-textured soils usually have more car- emissions (IPCC, 2007). bon retention capacity than sandy soils (Angers et al., In Cuba, there are extensively weathered tropical 2011). Based on the latter, the aims of this study were forests (Ferralsols, Nitisols, Oxisols, Lixisols, Acrisols, (1) to estimate the impact of different land uses on the and Alisols). The most extensive area is composed of fer- organic carbon stock (OC-stock) and (2) to determine the ralic Nitisol soil, especially in the western plains (in the clay percentage , the dispersion factor, and the bulk den- provinces of Artemisa, Mayabeque, Matanzas, and Ciego sity together with its implications for soil management. de Ávila), which, because of its profound and friable soil characteristics, has been the main source of food pro- Materials and Methods duction for the inhabitants of this region. There are antecedents in the study of red ferral- The study was carried out in the Mayabeque Prov- itic soils, and changes in the properties of these soils oc- ince, which is located in the western region of Cuba, cur under different forms of land use (Hernández et al., between 22° 34’, 23° 12’ North Latitude and 82° 28’, 2013). However, a fresh analysis of these studies pro- 81°40’ West Longitude, and is bordered on the west by duced a classification of the following three general pat- the Artemisa Province and on the east by the Matanzas terns: forests of > 40 years; forests conserved as pasture Province. This province comprises an area of 3,732.7 land (PL); and forests under permanent cultivation (CU). km2 under a sub-humid tropical climate with an annual However, the results presented by Batjes (1996) dem- precipitation of between 1,300 and 1,500 mm, a mean onstrate that variation in organic carbon is attributable temperature of 24.5 °C, and a plain relief. The material to its relationship to soil types and their management. of origin consists of Miocene-age hard limestone. For example, Olson (2013), and Olson et al. (2014) men- The soils under study (ferralic Nitisol) form part tioned that tillage systems influence soil organic carbon of the so-called “Red Grasslands of Havana,” which cur- Sci. Agric. v.74, n.4, p.311-316, July/August 2017 312 Hernández-Jiménez et al. Carbon loss of ferralic Nitisols rently cover the central-southern part of the Mayabeque Bouyoucos method, utilizing sodium pyrophosphate to and Artemisa Provinces, which were created three years destroy the microaggregates and sodium hexametaphos- ago. For more than two centuries, this area was cultivat- phate as dispersant; microaggregate composition by the ed, initially with tobacco and later with sugar cane, cof- Bouyoucos method but without chemical reagents; and fee, and other crops. Its natural formation under forests the dispersion factor (the k value) by dividing the per- resulted in fertile soils that are rich in organic matter, centage of clay obtained by mechanical analysis multi- which have been reported in other studies as storing a plied by 100. great amount of carbon due to the time factor involved Bulk density was determined by the cylinder in their formation and to the fact that they are profound method (100 cm3, volume). and friable soils (Morisada et al., 2003). An estimation of the carbon reserves (Mg ha−1) These soils have ABtC profiles, a deep red color was conducted using the following formula: and are made of clay. Table 1 presents a number of the chemical and physical characteristics of the soils for the CR = C (%) × Vd (kg/dm3) × Layer depth (cm) A and Bt horizons for each land use condition. These are soils with high base saturation. The range of pH values where: CR = Carbon reserves; C = Carbon; and Vd = is from slightly acidic (6.70) to slightly alkaline (7.30) in Volume density. the A horizon. However, in the Bt horizon, the range is The CR were calculated for depths of 0-20, 0-50, from strongly acidic (5.40) to neutral (6.90). Clay is from and 0-100 cm. 69 % in the A horizon to 87 % in the Bt horizon (argillic We carried out an analysis of variance (ANOVA) on horizon). the results considering a completely random design in The amount of calcium is predominant with total which the profiles of each category were considered rep- exchangeable bases from 10.10 to 18.18 cmol (+)/kg and etitions and each of the five conditions were considered these soils have high saturation. All of these character- treatments. We also carried out a means test (Duncan, istics demonstrate that the soils are eutric, lixic, and fer- 0.05) to evaluate the significance of the land manage- ralic Nitisols. ment over the OC-stock. Additionally, to test whether In total, 30 ferralic Nitisols soil profiles were stud- the data were normally distributed, we ran a Shapiro- ied under five conditions of coverage and land use which Wilk (W) statistic test. The statistical procedures were were grouped into various categories as follows: four un- conducted using PROC GLM and PROC MEANS in SAS der primary forests (PF) 80-100 years old (two of these (Statistical Analysis System, version 9.1). with ferro-manganese staining at a depth of 70-80 cm); two under secondary wood forests (SF) 45-50 years old; Results and Discussion eight under secondary young forests (YF) 15-25 years old; four under pasture lands (PL) 15-20-years old; and 12 The results demonstrate that the soils in this study, lands under continuous cultivation (CU) for > 50 years. when under permanent coverage, have a content of over The soils were identified by the World Reference 100 Mg ha−1 of organic carbon at a depth of 0-100 cm Base for Soil Resources (WRB) classification (Interna- (Table 2). The soils under the primary forests (80-100 tional Union of Soil Sciences (IUSS), Working Group, years old) have a higher OC-stock level (153.25 Mg ha−1), 2014). The soil samples were analyzed at San José de followed by the secondary forests (45-50 years old) with las Lajas, Mayabeque, Cuba, in accordance with the fol- 143.00 Mg ha−1; next, the young forests (15-25 years old) lowing analytical methods: organic matter according to with 124.00 Mg ha−1, and finally the soils under the pas- Walkley & Black; carbon by dividing the percentage of ture land accumulate 123.50 Mg ha−1. The forests and organic matter by 1.724; mechanical composition by the pasture land accumulate more organic matter than the Table 1 − Chemical and physical characteristics of soils for the A and Bt horizon under each land use condition.