Soil Ecosystem Services and Intensified Cropping Systems Kenneth R
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doi:10.2489/jswc.72.3.64A FEATURE Soil ecosystem services and intensified cropping systems Kenneth R. Olson, Mahdi Al-Kaisi, Rattan Lal, and Lois Wright Morton fforts to meet the food and energy needs of an expanding world pop- Figure 1 ulation have led to a large-scale Agroecosystem services provided by soil organic carbon (SOC) in corn-based crop- E ping systems of agriculture (adapted from Adhikari and Hartemink [2016], table 2). expansion and intensification of crop production systems. A major challenge Provisioning services of the twenty-first century is ensuring an • Food and fuel adequate and reliable flow of essential eco- • Raw materials system services (Biggs et al. 2012; Hatfield • Fresh water/water retention, purification and Walthall 2015) as cropping systems Regulating services are intensified. Ecosystem services are the • Climate and greenhouse gas regulation provisioning, regulating, supporting, and • Water regulation cultural functions that soil, water, vegeta- • Erosion and flood control tion, and other natural resources provide • Pest and disease regulation • Carbon sequestration Copyright © 2017 Soil and Water Conservation Society. All rights reserved. (MEA 2005). The conversion of natu- Journal of Soil and Water Conservation • Water purification by denaturing of pollutants ral ecosystems to cultivated cropland has eroded the capacity to efficiently retain Cultural services and sequester soil organic carbon (SOC) • Recreational/ecotourism • Aesthetic/sense of place (Olson et al. 2012), an essential ecosystem • Knowledge/education/inspiration service of soil, and created a paradox in our • Cultural heritage attempts to achieve sustainable agricultural • Therapeutical intensification, ecosystem resilience, and Supporting services human food security (Biggs et al. 2012). • Weathering/soil formation SOC stocks are critical to the provi- • Nutrient cycling sioning and regulating services (figure • Provisioning of habitat 1) that underlie the production of food, 72(3):64A-69A fresh water, air quality, erosion preven- tion, nutrient cycling, and support of environment (Hatfield and Morton 2013). management practices among corn-based habitat (Dominati et al. 2010; Adhikari Human activities and natural processes and corn-soybean based systems. And and Hartemink 2016). The health of have spatial and temporal effects on the it is these variations, such as type of till- www.swcs.org soil, its properties, formation and distri- capacities of SOC stocks to provide a age system, drainage systems, use of cover bution, processes, and interactions with flow of services. Soil degradation pro- crops, construction of grass waterways water, organisms and plants influence the cesses in intensified cropping systems and buffers, and terraces, which influence numerous functions and roles it serves affect SOC stocks and are one of the most whether SOC is retained, enhanced, and (Adhikari and Hartemink 2016). Further, dramatic examples of ecosystem deterio- potentially sequestered or is simply lost, how humans value the functions of soil ration (Swinton et al. 2007; Dominati et resulting in ecosystem degradation. The affects how soil is managed and its capac- al. 2010) limiting agricultural productiv- depletion of SOC as a result of soil deg- ity to deliver the variety of ecosystem ity and ecosystem health. Ecosystems and radation within intensified agricultural services needed to assure a sustainable human well-being are interdependent; systems can lead to loss of nutrients and thus, understanding the role of SOC as soil structure, loss of soil resilience, a loss a factor in the quality and type of eco- of soil biodiversity, and disruption to key Kenneth R. Olson is professor emeritus of the Department of Natural Resources and En- system services produced in intensified biotic and abiotic processes necessary for vironmental Sciences, College of Agricultural, production systems is central to develop- productivity (Lal 2015). The intent of this Consumer, and Environmental Sciences, Uni- ing effective management strategies that paper is to examine the interdependence versity of Illinois, Urbana, Illinois. Mahdi Al- guard against SOC stock depletion. of soil ecosystem services, SOC stocks, and Kaisi is a professor of agronomy, Department of Agronomy, College of Agriculture, Iowa State Cropping systems that are dominated human management. University, Ames, Iowa. Rattan Lal is a profes- by a single annual crop, such as corn (Zea sor in the School of Environment and Natural mays L.), are considered corn-based, while ECOSYSTEM SERVICES OF SOIL Resources, The Ohio State University, Colum- dual cropping systems, such as corn– ORGANIC CARBON STOCKS bus, Ohio. Lois Wright Morton is a professor of sociology, College of Agriculture, Iowa State soybean (Glycine max [L.] Merr.), are Soil plays a number of roles in providing University, Ames, Iowa. considered corn-soybean based. There is a ecosystem services associated with produc- great deal of variation in crop rotations and tion systems: fertility, filter and reservoir, 64A MAY/JUNE 2017—VOL. 72, NO. 3 JOURNAL OF SOIL AND WATER CONSERVATION structure, climate regulation, biodiver- Table 1 sity conservation, and resource use (table Roles of soil in the provision of ecosystem services (adapted from Dominati et 1) (Dominati et al. 2010). Two dominant al. [2010]). forms of carbon (C) contained in soil are Role Description of ecosystem service organic carbon (OC) and inorganic car- bon (IC), and in humid regions most of Soil fertility Plant growth is enabled by soil nutrient cycles that ensure fertility the C is held as SOC (with the exception renewal and deliver nutrients to plants. of calcareous soils). The term SOC refers Filter and reservoir Water is purified when soils fix and store solutes passing through to the C that occurs in the soil organic micro- and macroaggregates. Soil also cycles and stores water for matter (SOM) within the soil, and SOC plant use and mitigates flooding. comprises roughly 58% of SOM (historic Structural Soil provides physical support to plants for root development estimate that was recently questioned and anchoring. [Hussain and Olson 2000]). The SOC is Climate regulation Climate regulation can occur through soil carbon sequestration and most highly concentrated in the top 20 cm regulation of greenhouse gas (nitrous oxide and methane) emissions. (8 in) and decreases with soil depth down Biodiversity conservation Soil provides habitat for biodiversity, including diverse biological species to approximately 85 cm (33.5 in). Thus, and activities that affect soil structure, nutrient cycling, and detoxification. SOC contained within the top soil layer Resource Soil can be a source of materials like peat and clay. Pharmaceutical Soil microbes are sources of antibiotics. Copyright © 2017 Soil and Water Conservation Society. All rights reserved. is more likely to be affected by cultivation Journal of Soil and Water Conservation and management practices than deeper in Archival Soil is an archive of human and planetary history. the rooting zone. Cultural Soil is an inspiration to art and culture with spiritual values. The SOM, a key property of soil, con- sists of previously living plant and animal vices enhanced by SOC stocks are critical cropping systems that involve significant residues in different stages of decomposi- to achieving more sustainable production, amounts of tillage (Reicosky et al. 1997; tion. The SOM is a reservoir for essential management, and land use. Of particular Al-Kaisi and Yin 2005). Tillage intensity nutrients needed for plant growth and concern are the climate and greenhouse gas and soil degradation are among the major development, such as nitrogen (N), phos- (GHG) regulating services that SOC offers causes for the acceleration of SOC stocks phorus (P), sulfur (S), and micronutrients, under increasingly variable short- and long- loss or pool loss (Young et al. 2014). The and is one of the major binding agents of term weather patterns, which are affected mechanisms involved in loss of SOC stocks soil aggregation. It holds particles together by and in turn affect SOC stocks. The pres- or pool loss due to soil erosion as a result 72(3):64A-69A and creates soil pores within and between ervation of SOC is through C sequestration of intensive tillage can include SOM oxida- aggregates to provide air and moisture to processes that include the removal and stor- tion and degradation of SOC stock or pool the roots and drain excess water (Al-Kaisi age of CO2 from the atmosphere through (Guzman and Al-Kaisi 2010a; Lal 2003). et al. 2014). SOC is the main source of photosynthesis and storage in soil as SOM. The size of SOC pool is approximately www.swcs.org food for soil microorganisms. Soil aggre- These processes provide ecosystem services 2,300 Pg (2.5 × 1012 tn) to 2 m (6.6 ft) gates can be disrupted by tillage thereby by increasing SOC stock in the soil reser- soil depth, which is four times the biotic/ increasing the availability of C to micro- voir pools rather than in the atmosphere. vegetation pool and three times the atmo- organisms, which can result in release The monitoring of SOC stock over time spheric C pool. In contrast, the terrestrial 12 of carbon dioxide (CO2) back to the is a challenge, and SOC stock protocols C pool of 2,860 Pg (3.2 × 10 tn; 2,300 atmosphere. In addition to aggregation that quantify the anthropic impact as a Pg in soil, 60 Pg [6.6 × 1010 tn] in detritus characteristics, soil color is an indication result of management and land use changes material, and 560 Pg [6.2 × 1011 tn] in live of high or low SOC content. Darker soil must include baseline measurements to biomass) is 57% of the geological pool and has a higher SOC content than lighter measure change over time (Olson 2013). four times the atmospheric C pool (Lal colored soil. Increasing the level of SOM Other SOC regulating services are water 2003). Changes in the soil environment can increase a soil’s water holding capacity regulation through improvement of water can subsequently lead to chemical and bio- and make crops less susceptible to drought movement in soil, increased storage in soil, logical reactions (Troeh et al.