Keywords

4.1 Introduction

With the increasing growth of population, there is a greater demand for food. Thus, world agriculture has to be intensified. But land availability is still limited or even decreasing at increasing rate of urbanization. The per capita availability of land in India has decreased from 0.48 ha in 1951 to 0.12 ha in 2016 and projected to further reduce to 0.10 ha by 2025. Intensive agriculture needs higher doses of fertilizers for crop nourishment and pesticides for crop protection. Several intensive cereals or vegetables-based cropping systems have been practised by farmers across diversified ecology. Intensive agriculture, that is cultivation of high-yielding cereals and other crops which lead to nutrient depletion from the soil and use of chemical fertilizers and pesticides without any proper dosage, resulted in soil health degradation (John et al. 2001). Further, world agriculture is fully dependent on specific climatic conditions and specific management practices. These agricultural management processes could be substituted for biological functions, which affect the ecosystem’s natural balance (Kibblewhite et al. 2008) and lead to deterioration of soil quality. As of now, although organic agriculture is developed to sustain production, it is very costly and labour intensive and can’t provide demand-based food quantity. In addition to this all-out drive, soil health has also become major interest in developing areas, where the extensive production system has been intensified (Sinha et al. 2013). There is an increasing interest on the impact of cropping systems on soil quality to assess the physical, chemical and biological properties of soil in relation to crop production. In this review, we will discuss about how different soil groups show different responses in different cropping systems.

4.2 Concept of Soil Health

The term soil health is used as a synonym of soil quality. Soil quality is related to the function of soil (Letey et al. 2003; Karlen et al. 2013), whereas soil health represents a limited dynamic living resource which is non-renewable in nature (Doran and Zeiss 2000). Agricultural and environmental scientists in general prefer the term soil quality, and farmers or producers prefer the term soil health. Furthermore, soil health describes the biological virtue of soil microbial community that includes balanced interaction between organisms within soil and with their environment (Sinha et al. 2013).

Soil quality can be viewed in two ways:

  1. (i)

    As inherent characteristics of soil which is formed by combined effect of climate, topography, organisms, parent material and time (Jenny 1941). Therefore, soil has an innate capacity to function. Five soil functions as given by Karlen et al. (1997) are

    • Sustaining activity of soil microbes with their diversity and productivity

    • Regulation of water and solute flow

    • Buffering, degrading, immobilizing and detoxifying organic and inorganic toxic compounds which includes industrial wastes and by-products

    • Acting as storage of nutrients and other elements within Earth’s biosphere and continues to recycle it

    • Providing foundation archaeological structures and buildings associated with human habitation

  2. (ii)

    As a dynamic system of soils, influenced by climate and biosphere especially for human use. For example, erosion of surface layer with consequent loss of clay, organic matter and nutrients can’t be protected by only cropping system, and thus soil properties are degraded continuously over time. Larson and Pierce (1991) reported that approaches for evaluating soil health were (i) comparative (e.g. land use management) and (ii) dynamic assessment by measuring changes in soil quality attributes over time.

Physical, chemical and biological properties of soil interact in complex way to create a favourable environment in soil to perform. Thus soil quality cannot be measured directly but can be determined by measuring changes in its properties which are known to as indicators. Generally indicators are complex set of attributes which are derived from functional relationships and can be monitored with laboratory or field analysis, remote sensing or combinations of them. Soil indicators should

  • React to quick or slow change in management practices

  • Coalesce soil physical, chemical and biological properties

  • Be measured easily

  • Have a limiting or threshold value

  • Be stable for some time during analysis to enable measurement

  • Be sensitive to change in management practices

  • Be resistant to short-term weather pattern

Indicators as described in Table 4.1 which monitor the soil directly are grouped as visual (change in soil colour, gullies, ponding), chemical (soil pH, CEC, organic matter, nutrients), physical (soil structure, surface crust, B.D, hydraulic conductivity) and biological indicators (potentially mineralizable N, enzyme activity, soil microbial biomass/respiration).

Table 4.1 Major soil nutritional, chemical and biological indicators and related soil processes (Lal 1994)
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4.3 Cropping System in Relation to Soil Fertility and Productivity

Cropping system may be defined as sequence or order in which crops are grown on a piece of land over fixed period of time. Cropping system is an important component of a farming system. The productivity of land is maintained over time through proper soil management practices. Sustainable management is necessary for better germination, growth and yield of crops over the long run. Thus to maintain soil fertility as well as intensive cropping, soil should be cultivated with various crops that ameliorates soil as well as sustain minimum productivity. Depending on resource availability, different types of cropping systems are practised in different agroclimatic regions.

There is a growing consensus that comprehensive knowledge about the effect of continuous cropping on soil properties (physical, chemical and biological) is needed for the establishment of extent to which impacts on soil quality is quantized, thereby creating a sustainable cropping system (Aparicio and Costa 2007). Baseline values of soil properties have been assessed and determined in many parts of globe (Richter et al. 2007), including China (Ding et al. 2007; Wu et al. 2004), Canada (Zentner et al. 2001), India (Masto et al. 2008), the USA (Khan et al. 2007; Varvel et al. 2006), Nigeria (Oluwatosin et al. 2008), New Zealand (Lilburne et al. 2002; Murata et al. 1995), Sweden (Gerzabek et al. 2001; Gerzabek et al. 2006; Kirchmann et al. 2004), etc. From the experiments conducted in different agroecology, it has been observed that many suitable cropping sequences under different soils (Table 4.2) ensure and indicate the probable chances of maintaining soil fertility for next cultivation practices to follow.

Table 4.2 Diversification of crops: viable answers
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4.4 Farming System Diversity in Different Agroecological Regions Impacts on Soil Environment

A farming system is a combination of farm enterprise like cropping system, forestry, livestock, poultry and fishery, practised on farm to increase the profit of farmer per unit land. Without disturbing the effect of other components or ecological balance, the enterprises interact with each other in a synergistic manner. As different farming system is adapted in different agroecological regions, more of soil and water resources are being utilized differently according to the need-based practices, for example area under the small farmer community is being practised with crop and livestock production in combinations (McIntire et al. 1992). Now grassland is practised in all farming system as it adds more litters, high in C:N ratio and lignin:N ratio (Rasse et al. 2005); residence of C in grassland is much longer than others (Lemaire et al. 2014). Moderate grazing by cattle improves soil quality and increases soil C and N for longer periods of time (Franzluebbers and Stuedemann 2010). Hence multiple components of a farming system have multiple effects on modification of soil environment in different ecosystems. Some typical example of farming systems mediated changes in soil physical, chemical and biological properties have been provided in Tables 4.1 and 4.3.

Table 4.3 Farming system impacts on soil health differentially
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4.5 Lessons Learnt and Rephrasing Traditional Approach with Flexible Mode

Yield increment in last few decades is stagnated because of practices such as widespread cultivation intensification, development of high-yielding exhaustive varieties and increasing use of chemicals such as chemical fertilizers, pesticides, wastewater irrigation and farm-mechanization. According to researchers, intensive cropping areas should include legume-based cropping systems. Improved yield of crops followed by legume addition has been widely observed by farmers and recorded by researchers. As legumes with low C/N ratio, high rate of mineralization of organic N can fix atmospheric N2, breaks diseases and pest cycles in soil, improves soil microbial community and physical and chemical attributes and increases activity of soil macrofauna such as earthworms (Peoples and Craswell 1992; Kundu and Ladha 1995; Wani et al. 1995). Rotational benefits of annual legumes can be achieved by improving the N economy of soils assessed by reserves of organic N which is readily mineralizable in soil and microbial biomass C and N (Dalai et al. 1994; Rupela et al. 1995; Wani et al. 1995). The application of manure with balanced fertilization of N, P and K leads to lowering loss of nutrient and maintains soil organic carbon pool and soil microorganisms for long time. This in turn helps in transformation of nutrients. Again it has been time and again demonstrated that in areas having eroded soil where fertility is major constraints, conservation agriculture should be practised instead of conventional agriculture to sustain soil health and crop productivity for the long term (Govaerts et al. 2009; Hobbs et al. 2008). For eroded soil with flat plains, cost-effective stubble mulch or crop residue mulch gives conservation of moisture under field conditions as well as addition of organic matter with low soil temperature fluctuations. It protects soil from wind erosion. In dry semiarid areas and even in laterites, where soil lacks moisture content, ‘alley cropping’ should be followed. For example, black gram, turmeric, ginger, etc. crops are grown in passages formed by rows of eucalyptus, subabool, etc. to hasten soil fertility restoration by providing more organic litters, conserve moisture by providing shades and reduce soil erosion. Again continuous seashore winds or winds in nearby desert areas bury the croplands with sand when vegetation stabilizing the sand dunes is seriously damaged. Therefore stabilization or mitigation of sand dunes can be achieved by growing vegetation like ephemeral grasses, shrubs and trees with good rooting depth that traps sand because it is less expensive, stable over long period and self-repairing technique (Woodhouse 1978). In case of waterlogged soils, where anaerobic conditions prevail over the year can be used for cultivation of rice. For utilization of its full potential, reclamation through bio-drainage plants proved to be successful during course of 3–5 years. Bio-drainage plants are crops with higher transpiration rate with good rooting depth and are tolerant to waterlogging, for example Eucalyptus camaldulensis, willow (Salix spp.), poplar (Populus spp.) and alfalfa (Medicago sativa). They up take more of water from deeper soil depth and, after using it, transpire rapidly through the stomata of leaves. Continuous transpiration causes higher water levels to go down. Hence, fields become cultivable with more number of crops other than rice.

4.6 Conclusion

Diversification of cropping systems, an innovative movement with farmer-friendly approach, is necessary to get higher yield and return and to maintain soil health, preserve environment and meet daily requirement of human and animals. Thus, not only the number of crops, but type of crops included in the cropping sequence is also important. In this approach, resources are not only utilized efficiently but also ensure on a farm and their interactions with farm resources. Various cropping systems have different residual effects on different soils. Efficient nutrient management is prime concern in the management of optimum soil fertility. Hence, synthetic fertilizers should be applied in soil with optimal dose or little less along with organic manures because the maintenance of soil fertility as well as soil health can only be achieved through building up of soil organic carbon and proliferation of soil microbes. The sensitivity of soil indicators can provide information about dynamic nature of soil properties in field conditions. There is scope for further refinement to assess the soil quality parameters based on crop productivity under different soil types.