Globally, agriculture is entering a new era confronted with problems related to climatic change and issues of food security. Maize (
Zea mays L.), being a versatile and highly adaptive crop to diverse agro-ecologies with highest genetic yield potentials fundamental to ensure food and nutritional security to the millions
(Shiferaw et al., 2011; Jat et al., 2013). In India, maize occupies an area of ~ 9.8 M ha with annual production of ~19.8 million tones (
GOI, 2020-21). Among various maize-based rotation maize-fallow, maize-mustard, maize-chickpea, maize-maize, maize-potato, are the promising systems across the country. However, conventional maize production have several restraints, mainly due to poor crop establishment and inputs management
(Yadav et al., 2017; Parihar et al., 2017) leading to lower crop productivity and resource use-efficiency. Similarly, soils of the major maize growing are as low in soil organic matter (SOM) and nitrogen (N)
(Jat et al., 2014). In this context, CA-based maize rotation is being advocated as an alternative to conventional practices. The conservation agriculture concept is evolved in a response to the concerns of agricultural sustainability (
Bhan and Behra, 2014). Which is based on three fundamental inter-linked principles; (i) minimal mechanical soil disturbance, (ii) permanent soil cover and (iii) crop diversification (Fig 1). The years of intensive tillage had a remarkable negative outcome on the soil health
(Parihar et al., 2016) and resource use efficiency
(Govaerts et al., 2005) thereby affecting crop yields. Similarly, tillage practices also determine the content and distribution of SOM, which is a key indicator of a soil quality
(Thomas et al., 2007). Hence, proper optimization of tillage along with crop residue retention is necessary as it provides multiple benefits
viz. enhance soil microbial diversity, creates positive soil carbon/nitrogen stocks
(Melero et al., 2011; Parihar et al., 2018), improving water use efficiency
(Chauhan et al., 2000) and agronomic efficiency of applied fertilizer
(Kamanga et al., 2014). Therefore, this article reviews a performance of maize in relation to crop yield, resource use efficiency and different soil properties under CA-based tillage practices.
Principles of conservation agriculture (CA)
According to FAO conservation agriculture is based on three universally applicable and acceptable principles:
Minimum mechanical soil disturbance
This principle primarily focuses on the soil conservation. Practicing no-till system moderates SOM oxidation
(Ladha et al., 2009; Thomas et al., 2007), soil water movement (
Bhan and Behra, 2014), bulk density and soil resistance to penetration
(Saha et al., 2010) besides lowering cultivation expenditure
(Sharma et al., 2011).
Permanent soil cover through organic crop residues
In India, annual generation of crop residues is estimated around 500 MT (
GOI, 2016). Thus, the surplus residues can be recycled after being used for feeding cattle, cooking fuel and organic manure production
(Devi et al., 2017). Residue retention creates a favorable crop micro-climate, act as safeguard against beating action of rains
(Pimentel et al., 1995), reducing surface evaporation
(Tolk et al., 1999) and leads to improvement in soil physico-chemical and biological properties
(Jat et al., 2014). Recently, crop residue management using cover crops under CA is gaining much popularity across the globe (
Teasdale and Sharley, 1998;
Kuo et al., 1997).
Crop diversification
Diversifying crops fulfills human dietary requirement (
Bhan and Behra, 2014), stabilized income / crop productivity
(Das et al., 2014), provides protection against pest / disease / weed infestation
(Howard et al., 2003) and also improves soil productivity
(Stagnari et al., 2009). In this regard, the Government of India (GOI) had also initiated several schemes for promoting sustainable crop diversification to address the burning issue of agriculture and allied sectors.
Impact of CA-based tillage practices
Yields levels
Globally, ever-growing population and shrinking land resources has threatened sustainable crop production. Hence, sound agronomic intervention plays an important role to ensure food and nutritional security. The CA-based tillage practices has come up to achieve maximum production potential through sustained agronomic productivity. The study (six year) conducted by
(Parihar et al., 2016), in NW-IGP of India, had documented 9.4-12.2% greater pooled grain yield and highest system productivity (11.3-12.9 Mg ha
-1) with CA-based tillage practices. Several other studies also conform the higher maize yield ranged from 17-19% with CA-based practices (Bachmann and Friedrich. 2002;
Blanco-Canqui et al., 2006;
Kaschuk et al., 2010; Das et al., 2014; Singh et al., 2014). While,
Jat et al., (2006) reported marginally lower maize yield under zero-tillage system due to more infestation of perennials weeds. The maize planted on permanent–bed resulted in enhanced maize yields compared CT practices
(Potter et al., 1996). Likewise,
Aquino et al., (1998) had also reported yield advantage of wheat, maize and soybean under raised bed planting. Which was in consistent with the investigation of
Jat et al., (2013) in which maize on raised bed provides substantial yield advantage up to 24-40% compared to CT based practices. Similarly,
Ram et al., (2010); Jat et al., (2006); Kumar et al., (2004); Govaerts et al., (2005); Thierfelder et al., (2018) concluded that higher maize yield under CA based system might be attributed to better water regimes, compound effects of additional supply of nutrients and improvement in soil physical properties, improved soil carbon status resulted from residue imbedded tillage with practices.
Resource use efficiencies
The inefficient resource use in conventional practices leading to declining factor productivity and low input use efficiency. Several studies conducted in past demonstrated the effects of CA based tillage practices exclusively on input use efficiencies such as higher water use efficiency
(Chauhan et al., 2000), higher energy output, increased energy productivity and net energy
(Parihar et al., 2017; 2018). Similarly, Jain
et al. (2007) also reported higher energy-use efficiency and energy productivity under conservation tillage relative to traditional practices. Out of total operational energy, 1/3
rd of energy and 36 liters ha-1 of diesel (equivalent to minimizing CO
2 emission of 93 kg ha year
-1) could be saved under ZT system compared to CT based practices (Srivastava, 2003; Erenstein and Laxmi, 2008). Similarly,
Jat et al., (2014) had reported significantly (
P<0.05) higher carbon sustainability index (CSI) and carbon efficiency (CE) with permanent bed planting followed by zero in maize-maize-sesbania system and they concluded as did by
Dubey and Lal, (2009). However,
Kamanga et al., (2014); Six
et al. (2004) had registered contrast results regarding nutrient use efficiency under CA-based tillage practices.
Soil chemical properties (pH, SOC, N, P and K)
Soil chemical environment can be modified through different agronomic practices and maintenance is equally important to achieve higher crop growth and productivity. The CA-based tillage
viz. ZT and PNB had a remarkable positive impact on the chemical properties as it preserves organic matter content and improves status of different nutrient in the soil (
Wright and Hons, 2004;
Owens et al., 2002). Similarly, Govaerts
et al. (2007) observed linear relationship of soil organic matter with an amount of straw retention under permanent raised bed system. Similar findings were also obtained by Lal. (1997); Hulugalle and Entwistle (1997);
Utomo et al., (2013). Likewise, Parihar
et al. (2016) had reported 23.6-35.3% higher soil carbon content at 0–15 cm soil depth under CA based tillage pertained to CT practices. However, several other studies confirmed higher SOC ranged from 19.4 to 67% with CA based practices at 0-30 cm soil section compared to maize planted on CT plots
(Thomas et al., 2007; Kaiser et al., 2014; Six et al., 2004; Das et al., 2014) (Table 1). The adoption of CA-based tillage in conjugation with crop residues residue retention hold potential to influences soil total and mineralizable–N content
(Gosai et al., 2009), available soil nitrogen status (
Mohanty and Mishra, 2014), extractable–P content and K content in the surface soil layer
(Ismail et al., 1994). Which was ascribed to less leaching, fixation and release of several chelating agents resulted from improvement in soil properties due to optimization of tillage and crop residue management under CA based cropping system
(Betrol et al., 2007; Du Preez et al., 2001; Robbins and Voss 1991;
Standley et al., 1990).
Soil physical properties
Tillage practices have a direct impact on soil physical health. It modifies water regimes, root proliferation/penetration into the soil and controlled the absorption of soil nutrient by the plants. The ZT technology proved to be a wise choice to improve the overall soil physical health. Several findings suggested that maize when planted under no-tilled plots had shown a significant (
P<0.05) improvement in soil bulk density, infiltration rate, hydraulic conductivity and penetration resistance and other related physical properties relative to CT based system
(Wilkins et al., 2002; Afzalinia and Zabihi, 2014;
Lampurlanes and Cantero-Martinez, 2006;
Lal, 2000;
Jat et al., 2005; Parihar et al., 2016). However, some researchers had reported a non-significant results with respect to soil bulk density with no-tillage system
(Gwenzi et al., 2009; Horn, 2004;
Ram et al., 2002; Kumar et al., 2002). Similarly,
Yang and Wander (1999) and Salem
et al. (2015), concluded that changes in soil physical properties is mainly attributed to lesser trafficking of machinery along with proper crop residue management under zero tillage in comparison with CT practices.
Soil biological properties
The soil has the most diversified population of flora and fauna and it has been estimated that the 1 gram of soil contains millions of living organism like, bacteria, fungi, mycorrhiza, protozoa, nematodes, earthworms, mites, enchytraeids ants, termites, beetles and spiders
etc. (
Hawksworth, 1991). Higher soil microbial population and soil enzymatic activities are supposed to be key factors for nutrient cycling in an agro-ecosystem (
Dick, 1994;
Hungria et al., 2009; Salinas-Garcia et al., 2002). Long-term adoption of resource conservation practices along with residue retention often increase microbial populations, biomass and enzymatic activities by providing substrates for their growth
(Stott et al., 2009; Singh et al., 2009). Which in turn nourishes soil through nutrient recycling back to the soil system
(Marinori et al., 2000; Singh et al., 2009). It has been documented that CA-based maize rotation can increase soil microbial biomass carbon (SMBC) and dehydrogenase activity up to 25-80% and greater than 100% compared to CT practices (Table 2). The undisturbed soil, more vertical distribution of organic residues, improved aeration and water content are responsible for higher enzymatic activity under zero tillage system.
(Melero et al., 2011; Green et al., 2007; Roldan et al., 2007; Ladd, 1985). The long-term study conducted by Parihar
et al. (2016) had also reported higher (on average 45-48.9%) improvement in soil microbial biomass carbon (MBC) and soil enzymatic activities
i.e., fluorescine diacetate, dehydrogenase, b glucosidase and alkaline phosphatase at 0-30cm soil depth under CA based systems. Similarly,
Kladivko, (2001) suggested that, microbial diversity is negatively correlated with the intensity of tillage. Which was in similar line with the results of
Ferrerus et al., (2000) and
Hassen et al., (2007).
