doi:10.2489/jswc.74.3.55A Eco-intensification through sequestration: FEATURE Harnessing services and advancing sustainable development goals Rattan Lal

and misuse and soil mismanagement, and ITPS 2015; Lambin et al. 2013). The objective of this article is to describe prin- causing trauma and severe deg- additional demand for land is ciples and techniques of EI through soil C L radation (Steinbeck 1939; Jacks and exacerbated by soil degradation (Oldeman management and sequestration, and explain Whyte 1939; 1951; Buck 2012), 1994) and conversion to nonagricultural technological options including importance must be replaced by a judicious uses including urbanization (Lal 2017). of CA systems. This review is based on the and prudent soil/crop/ management As much as 25% of the agricultural land hypothesis that the dilemma of degrad- to restore degraded and improve the resources are strongly degraded (Oldeman ing agricultural soils and increasing environment. The rapid increase in agri- 1994; Bai et al. 2008; Bindraban et al. 2012; demand can be effectively addressed through cultural production since the 1960s has FAO and ITPS 2015; Rekacewicz 2008), restoration of by SOC sequestra- been caused by massive input of fertil- and the risks of additional degradation tion and the attendant improvement in soil izers ( [N], phosphorus [P], and may be exacerbated by the projected cli- quality through the strategy of EI. potassium [K]), pesticides, use in mate change because of possible increase plowing and other farm operations, and in precipitation intensities (Michael et al. ECO-INTENSIFICATION AND 8 Copyright © 2019 Soil and Society. All rights reserved.

of about 350 Mha (8.645 × 10 2005). Identifying systems of maintain- CONSERVATION Journal of Soil and Water Conservation ac) of land (Smil 2003; Tilman et al. 2001; ing or improving agronomic productivity, EI is defined as intensification of biological Arizpe et al. 2011; Gomiero 2016). How- without degrading or pollut- processes supporting ecosystem services on ever, such an indiscriminate intensification ing the environment, is an important goal medium-term (efficiency of management through plowing, -based irrigation, especially in emerging economies (e.g., options) and long-term (sustainability of and high inputs of chemicals has strong India and China). Further, soils of agro- management option) basis (Gaba et al. adverse effects on the quality and func- must be managed in a manner 2014). A system-oriented CA (Lal 2015) tionality of soil, water, air, , and that minimizes adverse impacts on the encompasses a site-specific combination of (Benson 2014). Despite these environment. An effective control, (1) NT, (2) residue mulching, (3) complex massive inputs, agronomic production of based on sound measurement techniques rotations including cover cropping during food staples has stagnated in some regions (Brandt et al. 2018), and prevention of soil the off-season, and (4) integrated nutri-

(Grassini et al. 2013), and new approaches structural degradation (Grandy et al. 2002) ent management based on a judicious use 74(3):55A-61A to food production must be identified in are important considerations. Thus, there is of organic and inorganic sources of the face of change (Beddington et a need for a paradigm shift in managing nutrients. The strategy is to fine-tune a al. 2012; Foley et al. 2011; Lal 2016a, 2018). soils of agroecosystems. site-specific system that creates a positive Thus, the use of nutrients and pesticides, as Eco-intensification (EI), designed to soil/ecosystem C budget on a long-term www.swcs.org well as rates and mode of application, in restore soil organic carbon (SOC) and soil basis. Thus, the input of -C into the agroecosystems must be revisited (Drink- inorganic C (SIC) stocks of degraded soils, soil (by residue retention, cover cropping, water and Snapp 2007). is an option to bring about the desired and amendments) must exceed the losses

Advancing food security has numerous paradigm shift. Sustainable management of (by decomposition, erosion, and leach- dimensions: reducing waste, improving SOC, to maintain stocks above the thresh- ing). While decomposition of biomass is distribution, increasing access, enhancing old level of 1.5% to 2.0% in the root zone, essential to maintaining the desired activ- retention by improving human health, is essential to sustaining productivity while ity and species diversity of soil biota, losses and increasing agronomic production. For restoring the environment. The SOC stock of SOC by accelerated erosion (though meeting the food demand of 9.8 billion by may be enhanced by land use and man- water, wind, , gravity, etc.) must be 2050 with growing preferences for animal- agement systems that create a positive C curtailed. Basic concepts of CA are also based diets, it is argued that the agronomic budget in the root zone. The strategy of EI in accord with those of EI for “produc- production may have to be increased by may be implemented through adoption of ing more from less” by enhancing the use 70% to 110% of the level in 2005 (FAO conservation agriculture (CA). Conversion efficiency and reducing losses (Lal 2010). 2002; Alexandratos and Bruinsma 2012; of conventional plowing to CA (based on The goal is to produce more per unit area Bruinsma 2009; Gomiero 2016), along no-till [NT], mulch farming and cover of land, and pesticides, irrigation, with increase in the cropland area by as cropping, complex rotation, and integrated energy, and emission of greenhouse gases. much as 150 Mha (3.71 × 108 ac) (FAO nutrient management) may enhance SOC With this strategy, the land area needed for concentration and also reverse the soil cereal production can be decreased rather Rattan Lal is a distinguished university profes- degradation trends. While CA is neither a than increased (Lal 2016a). sor of and the director of the Car- panacea nor a one-size-fits-all, the goal is Whereas the usefulness of CA has been bon Management and Sequestration Center at The Ohio State University, Columbus, Ohio. to make it work for site-specific conditions recognized since the 1940s (Faulkner because of numerous cobenefits. Thus, the 1943), its adoption on about 180 Mha

JOURNAL OF SOIL AND WATER CONSERVATION MAY/JUNE 2019—VOL. 74, NO. 3 55A (4.45 × 108 ac) of cropland (Kassam et al. CONSERVATION AGRICULTURE AND al. (2014) indicated that SOC concentra- 2019) is primarily limited to large-scale SOIL ORGANIC CARBON: SOME tion in 0 to 30 cm (0 to 11.81 in) depth commercial farms in North and South SUCCESS STORIES was significantly higher in NT than con- America, , and New Zealand. There are some examples of positive ventional tillage by 10% more in Declining (physical, chemical, results of CA on agronomic yield and and 8% more in , but no differ- and biological) and incidence of weeds SOC sequestration. In the Plateau of ence in Luvisol. The average SOC stock are addressed in large-scale farming by China, Lu et al. (2018) reported a positive in 0 to 30 cm depth was 29.4 Mg C ha–1 inputs of agrochemicals and use of other net ecosystem C value for a mulch-based (13.11 tn C ac–1) under NT and 27.4 Mg energy-based inputs. However, lack of CA system and a negative value with con- C ha–1 (12.22 tn C ac–1) under conven- appropriate seeding drills and competing ventional moldboard plowing. Further, Lu tional tillage, an average increase of 0.4 Mg uses of crop residues remain to be serious and colleagues observed that conversion C ha–1 y–1 (0.18 tn C ac–1 yr–1). obstacles to adoption of CA by - from plowing to CA caused SOC seques- On a long-term basis, effectiveness of poor small landholders (Johansen et al. tration at the rate of 0.84 to 2.69 Mg C CA on SOC sequestration depends on a 2012). Capital and labor constraints also ha–1 y–1 (0.37 to 1.2 tn ac–1 yr–1). In the wide range of interacting factors includ- limit adoption of CA by small landhold- southeastern United States, Franzluebbers ing climate (especially the rainfall and its ers (Grabowski 2011). Thus, there is a (2010) observed that the rate of SOC distribution) along with soil temperature strong need to link researchers, farmers, sequestration with adoption of CA was regimes, soil properties, the amount and –1 –1 Copyright © 2019 Soil and Water Conservation Society. All rights reserved.

and industry stakeholders to promote the 0.45 ± 0.04 Mg C ha y (0.20 ± 0.02 quality of the input of biomass, and the Journal of Soil and Water Conservation adoption of CA (Naresh et al. 2014). tn C ac–1 yr–1). Analyzing data from long- . Virto et al. (2012) con- There are also concerns regarding a term field experiments in the United cluded that the C input differences may possibility of low crop yields and low States, Allmaras et al. (2000) reported the be the main factor explaining the vari- or no accumulation of SOC by CA in SOC storage in the order of NT > non- ability in SOC storage in CA compared to degraded and depleted soils of both large moldboard tillage > moldboard tillage inversion-tilled systems. Removal of stub- and small landholder farmers. With the system. Based on a 24-year study con- ble for and other uses can reduce use of crop residue mulch and a system- ducted in southern Illinois, United States, SOC stocks. Modeling studies in the state based approach, however, adoption of CA Olson et al. (2013) reported that NT plots of Baden-Württemberg (southwestern by small landholders can enhance and retained 7.8 Mg C ha–1 (3.48 tn C ac–1) Germany) by Gaiser et al. (2008) indicated sustain productivity under harsh condi- more and chisel plow –1.6 Mg C ha–1 the SOC sequestration rate of 0.08 to 1.82

tions of rainfed farming (Rockström (–0.71 tn C ac–1) less SOC in the soil than Mg C ha–1 y–1 (0.036 to 0.081 tn C ac–1 74(3):55A-61A et al. 2009). A pertinent answer to the moldboard plow. Further, the long-term yr–1) in the state territory of 35,742 km2 question of whether CA is a solution productivity compared favorably with that (13,800 mi2). Under conventional tillage, to dryland farming by small landhold- of conventional tillage. Also, in southern mean SOC losses through erosion were ers is appropriately given by the positive Illinois, Walia et al. (2017) evaluated till- estimated at 0.45 Mg C ha–1 y–1 (0.20 tn www.swcs.org results obtained from eastern and south- age and management effects C ac–1 yr–1). In the Colombian Andes, ern Africa (Kinyumu 2012; Araya et al. on SOC concentration to 1 m (3.28 ft) Quintero (2009) reported that SOC con- 2015; 2016) and elsewhere (Lal 2016b). depth after 44 years of cultivation. Walia centration in the whole profile was 29%

Debate regarding the effects of CA on and colleagues observed that NT manage- higher under CA than that under conven- SOC sequestration and agronomic pro- ment increased SOC stocks and was even tional tillage, and that SOC sequestration ductivity (Govaerts et al. 2009; Powlson greater than that in the chisel tillage and especially occurred in the . Transfer et al. 2011; Baker et al. 2007; Pittelkow soil to 1 m depth. The rate of SOC of SOC in the subsoil is enhanced by the et al. 2015), including the common sequestration in NT for the top 15 cm (5.9 activity and species diversity of soil biota observation that CA merely affects the in) depth over 44 years was 0.36 Mg C such as . Yet, there exists an distribution of SOC (stratification) in ha–1 y–1 (0.16 tn C ac–1 yr–1). Based on a urgent need to understand processes and the surface layer rather than increasing its 13-year study in a semiarid Mediterranean identify appropriate management options total amount (Piccoli et al. 2016), neces- agroecosystem of Lleida, Spain, Morell that enhance activity and species diver- sitates studies of a detailed soil/ecosystem (2012) concluded that SOC stock under sity of soil biota, enhance soil health, and C budget along with long-term measure- NT increased by 4.3 and 3.9 Mg C ha–1 restore SOC stock. This is where systems ments of SOC stocks to ~1 m (3.28 ft) (1.92 to 1.74 tn C ac–1) in comparison to of EI can play a pivotal role. depth, and adopting site-specific manage- minimum tillage and conventional till- ment systems that create a positive soil C age. Further, input of medium and high N TOWARD MAKING SOIL OF budget. Indeed, C-input differences is the fertilization increased SOC stock by 3.4 AGROECOSYSTEMS A main factor explaining the variability in and 4.5 Mg C ha–1 (1.51 and 2.00 tn C Soils of agroecosystems, croplands and SOC storage in NT compared to inver- ac–1). A 5-year study conducted in cen- pasturelands combined, cover about 5 sion tilled systems (Virto et al. 2012). tral Morocco on three soil types (Vertisol, Gha (1.24 × 1010 ac) of manageable Cambisol, and Luvisol) by Moussadek et land area for soil C sequestration (table

56A MAY/JUNE 2019—VOL. 74, NO. 3 JOURNAL OF SOIL AND WATER CONSERVATION Table 1 1). Site-specific adaptation of a system- Global land use (modified from Lal [2018] and FAO [2018] publications). based CA has a potential to make these soils a sink of atmospheric Land use Land area (106 ha) Percentage of the total -free land area (%) (CO2). Important determinants of SOC Cropland 1,590 12.0 sink capacity of agroecosystems depend Pasture land 3,270 25.0 on numerous interacting factors (figure Forest land 4,000 30.0 1), including (1) pedo-climatic factors (managed and natural) comprising of soil properties and climate Urban land 730 0.6 parameters; (2) agroclimatic parame- Other 4,070 32.4 ters comprising of judicious agronomic Total 13,000 100.0 management especially that of nutrients, rotation, water, and integration with trees

Figure 1 Determinants of making soil under conservation agriculture (CA) a sink of atmospheric carbon dioxide. INM refers to integrat- ed nutrient management based on judicious combination of organic and inorganic sources. Copyright © 2019 Soil and Water Conservation Society. All rights reserved. Journal of Soil and Water Conservation Soil properties • Texture • Structure • Depth • Climate minerology • Water retention • Internal • position • Erodibility

Edaphological 74(3):55A-61A Pedo-climate factors determinants Climate Input of biomass carbon • Rainfall amount and • Residue management www.swcs.org distribution • Surface mulching Determinants of CA as a • Temperature regime • Vertical mulching carbon sink • Midseason drought • Biofuel effluent • Soil temperature regime

• • Erosivity • Manurin g

Agroengineering Agroclimate variables parameters Agronomic management • Nutrient input (INM) • Rotation • Cover cropping • Agroforestry • Grazing system • Water management

JOURNAL OF SOIL AND WATER CONSERVATION MAY/JUNE 2019—VOL. 74, NO. 3 57A (agroforestry) and livestock (agropastoral); mental impact of organic farming (OF), the meaning of the term SI is neither (3) agroengineering variables with regards sustainable intensification (SI), and EI clear nor used in a standardized manner to residues management, surface mulching, (table 2).The principal strategy of SI is to (Andres and Bhullar 2016; Petersen and vertical mulching, application of effluent increase production from existing farm- Snapp 2016). There is also a lack of focus from biofuel feedstocks (i.e., Miscanthus land while restoring the environment on improving soil health by restoring soil [Miscanthus × giganteus]), and use of bio- (Garnett et al. 2013; Pretty 1997; Pretty C (SOC and SIC) stocks through increas- char; and (4) edaphological determinants et al. 2011; De Vivo et al. 2016; Tilman et ing inputs of biomass-C in soil. Thus, the of physical management of soil surface al. 2011). However, innovative agroecosys- term EI is more focused and specifically to reduce risks of crusting, compaction, tems must also be pertinent to adapting directed to improving soil health and the poor aeration, and water imbalance (the and mitigating , improving attendant processes (Peterson and Snapp drought-flood syndrome). Because there is quality and renewability of water, enhanc- 2016), and bringing about the much no universal CA system, adaptation of CA ing biodiversity, and advancing Sustainable needed paradigm shift (Tchamitchian et al. to site-specific environments (biophysical Development Goals (SDGs) of the United 2011). Because of its relation to the envi- and socioeconomic) is important to har- Nations. The needs for increasing food ronment on the one side and the human ness the potential SOC sink capacity. production and meeting other demands dimensions on the other (figure 2), EI is of growing and increasingly affluent world focused on restoring and sustaining soil SUSTAINABLE SYSTEMS OF population must be met by adopting sys- health through improvement of soil C and Copyright © 2019 Soil and Water Conservation Society. All rights reserved.

ECO-INTENSIFICATION tems of land use and soil/crop/animal strengthening its capacity for provisioning Journal of Soil and Water Conservation There are notable differences in concepts, management that also restore quality of of ecosystem services. management, productivity, and environ- soil and other natural resources. Further,

Table 2 Comparative analysis between organic farming, sustainable intensification, and eco-intensification. Parameter Organic farming Sustainable intensification Eco-intensification Fertility management Managing , Using chemical fertilizers Integrated nutrient management enhancing soil biological activity, based on a judicious combination biological nitrogen fixation (BNF) of organic and inorganic sources,

biomass recycling, and BNF 74(3):55A-61A Disease and pest Crop rotations, natural predators, Chemical pest control: herbicides, Integrated pest management, creating management resistant varieties, diverse fungicides, insecticides disease suppressive soils, judicious cropping systems chemical intervention, and enhancing biodiversity Seedbed preparation Mechanical tillage for weed control, No-till based on chemical weed control Conservation agriculture based on a www.swcs.org residues incorporation, and system approach: (1) residue mulch, management (2) no-till, (3) complex rotations, (4) cover cropping, (5) integrated

nutrient management Water management Soil-water conservation Supplemental irrigation, drip-fertigation conservation, minimal supplemental irrigation, resilience against drought-flood syndrome Environment management Strengthening biodiversity, Minimal biodiversity High soil biodiversity, good soil health, minimizing chemical release better environment quality Risks of soil degradation No soil pollution but high risks of soil High risks of soil pollution by chemicals Conservation-effective with minimal and pollution erosion because of mechanical tillage risks of soil degradation and environmental pollution Agronomic yield Low High but not sustained Optimal but sustained with creation of better environment and regreening of landscape Gaseous emission Low Very high Moderate and often emission-negative System approach High diversity of crops, integrated Improved varieties grown with high input Integrated soil-crop-livestock-tree with trees and livestock of fertilizers and supplemental irrigation systems to enhance soil and environmental health by using conservation agriculture and sequestering carbon

58A MAY/JUNE 2019—VOL. 74, NO. 3 JOURNAL OF SOIL AND WATER CONSERVATION Figure 2 be avoided. Thus, EI implies harnessing of Eco-intensification of agroecosystems for harnessing ecosystem services and ecosystem services (Bommarco et al. 2013) advancing Sustainable Development Goals of the United Nations: #1 no poverty; while restoring soil resources, mitigating #2 zero hunger; #3 good health and wellbeing; #6 clean water and ; #11 gaseous emissions from agroecosystems sustainable cities; #13 climate action; #15 on land; and #16 peace, justice, (Burney et al. 2010), and sustaining pro- and strong institution. ductivity. The need for a paradigm shift in agroecosystems (Fedoroff et al. 2010) can be met through EI (Hochman et al. Agronomic and forestry 2013) by farming for ecosystem services productivity (Robertson et al. 2014) while advancing • Nutritional quality the SDGs (figure 2). • Safety • Sustainability CONCLUSION • Urban agriculture Soils of agroecosystems are an impor- tant sink of atmospheric CO . With the Environmental quality 2 necessity of limiting the global warming • Soil to 1.5ºC (2.7ºF) and restoring the envi-

• Water Copyright © 2019 Soil and Water Conservation Society. All rights reserved. Eco - • Air ronment, the strategy is to manage soils of Journal of Soil and Water Conservation intensification SDG #2, #11 • Landscape agroecosystems to harness ecosystem ser- • CA SDG #15 • Efficient use of all • Biodiversity vices while restoring the environment and inputs advancing SDGs of the United Nations. Positive soil and • Drip fertigation The needed paradigm shift in agriculture ecosystem carbon • Continuous soil (organic and can be met through adoption of the strat- cover inorganic) budget egy of EI, which implies managing soils • Integration of crops of agroecosystems to be climate-resilient with trees and SDG #13 Climate action livestock by adapting and mitigating anthropogenic • Perennial grains SDG #1, #3 climate change, improving quality and #6, #16 • Adaptation and mitigation renewability of water, enhancing biodi-

• Climate-resilient versity, improving human wellbeing, and 74(3):55A-61A agriculture conserving nature. There are notable dif- ferences in concepts, practices, and soil/ environmental impacts among OF, SI, Human dimensions and EI. The latter involves the concept of www.swcs.org • Social equality producing more from less while restoring • Poverty alleviation soil health and improving the environ- • Cohesion ment. Examples of farming practices for • Wellbeing

adopting EI include CA, perennial culture, and integration of crops with livestock. Because CA may neither always pro- duce the desired yield nor sequester soil C, fine-tuning based on a soil-guide and The goal of OF is to eliminate the use Neglecting soil and and techniques that create a positive soil/eco- of chemicals; it has its niches, but also increasing productivity through plant system C budget (e.g., cover cropping limitations (table 2). However, EI is not improvement alone has and can create and activity) must be identi- limited to OF per se. The strategy of EI serious environmental hazards. In contrast, fied. The goal is to adapt the CA system involves judicious use of inputs (both EI in conjunction with improved germ- and make it work because of its numer- organic and inorganic) to meet the soil/ plasm is a real paradigm shift because it ous cobenefits. While OF has its niches, farming system demands for nutrients, also minimizes the risks of environmental EI implies a judicious/prudent use of all water, and pest control. The impact of EI degradation. Adoption of EI is critical to inputs (organic and inorganic), improving goes beyond increase in agronomic pro- enhancing soil quality/health (Bünemann use efficiency and reducing their leakage ductivity. The latter can be achieved by et al. 2018) and to developing climate- into the environment. genetic engineering and biotechnology resilient systems against the drought-flood on a short-term basis (South et al. 2019), syndrome. Excessive and indiscriminate REFERENCES but it cannot be sustained unless soil use of chemicals, leading to pollution, Alexandratos, N., and J. Bruinsma. 2012. World health and are also enhanced. contamination, and eutrophication, must agriculture towards 2030/2050. ESA Working

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