Abstract
Climate change is a major threat to food security. The global population is increasing at a stimulated rate. Wheat and maize are the globally important crops. There is a need to focus on the methods that help to improve crop production. Since, conventional tillage (CT) is the major tillage practice in rain-fed areas. Conservation tillage methods are practiced to conserve soil moisture in order to increase crop productivity. However, the effects of conservation tillage methods under varying soil textures, precipitation and temperature patterns are still unknown. We took data from 119 peer-reviewed published articles and carried a meta-analysis to assess the effects of 3 conservation tillage practices including no tillage (NT), reduced tillage (RT) and subsoil tillage (ST) on precipitation storage efficiency (PSE), soil water storage at crop planting (SWSp), grain yield, evapotranspiration (ET) and water use efficiency (WUE) under varying precipitation and temperature patterns and soil textures in dry land wheat and maize cropping systems. We took conventional tillage as a control treatment and compared it with different types of fallow conservation tillage systems. Compared to conventional tillage (CT), conservation tillage methods overall increased PSE, SWSp, grain yield, ET and WUE by 22.6%, 17.8%, 24.1%, 6.5% and 12.1%, respectively in winter wheat. Among conservation tillage methods, NT had a better performance on SWSp, grain yield and WUE compared to RT and ST. Fine-textured soils showed better response of tillage methods on PSE, SWSp and ET than medium and coarse-textured soils, while medium-textured soils showed greater positive response ratio (RR) of conservation tillage methods on grain yield and WUE. The enhancement of conservation tillage on PSE and grain yield was greater in the regions having mean annual precipitation (MAP) of >600 mm, while crop yield, ET and WUE were greater when MAP was <400 mm. Conservation tillage methods also increased PSE, grain yield and WUE in the regions where mean annual temperature (MAT) was 8-15 ℃, while SWSp was greater when MAT was <8 ℃. In dryland spring maize, conservation tillage overall increased PSE, SWSp, grain yield, ET and WUE by 38.1%, 20.6%, 29.6%, 16.9% and 11.0%, respectively. The regions having medium-textured soils showed better response of tillage methods on PSE, SWSp, ET and WUE, while coarse-textured soils showed greater positive response ratio (RR) of tillage methods on grain yield. Compared to CT, the RR of conservation tillage on PSE, grain yield, ET and WUE was greater when MAP was <400 mm, while SWSp was greater when MAP was 400-600 mm. Conservation tillage also increased PSE, SWSp and ET in the regions where MAT was <8 ℃, while grain yield and WUE were greater when MAT was >15 ℃. We conclude that NT is a global promising practice among all conservation tillage methods to increase soil water storage and crop production under varying precipitation and temperature patterns and soil textures in both winter wheat and spring maize cropping systems.
Keywords: Conservation tillage, soil water conservation, crop production, food security, climate change.
Introduction
Climate change is seriously endangering humans and biodiversity by impairing agricultural productivity (FAO, 2020; Chandio et al., 2021). The climatic changes related to floods, changing patterns of rainfall and temperature and draining water reservoirs are affecting the major agricultural crop production (Appiah et al., 2018; Abbas, 2020). Global hunger and food insecurities are continuously rising as a result of the remarkable rise in population around the world and the agriculture sector’s stagnant performance. One of the main goals of the SDGs is to eradicate hunger and provide food security.
Food security is achieved when all people at all times have physical and economical access to sufficient, safe and nutritional food to fulfill their dietary needs and food preferences for an active and healthy life (FAO, 1996). The major factor contributing to global food insecurity is climate change (FAO, 2017). To cope food insecurity, there is a need to develop methods that are helpful in increasing crop production. Different factors such as poor seed management, soil infertility, water scarcity and expensive field treatments are playing major role in declining crop productivity (Abdullaev et al., 2007). Countries such as Middle East and Australia are facing the soil problems because of land changes, deforestation and climatic conditions that bring more detrimental effects in arid and semi-arid conditions (Nosrati and Collins, 2019; Zeraatpisheh et al., 2020). Future plans may focus on development of land for agriculture sector within populations of different communities without depleting natural resources (Broman and Robèrt, 2017). Sustainable agriculture is basic part in making long term plans for land development such as these strategies have low environmental hazards and better crop production (Busby et al., 2017). Sustainable agriculture is ecofriendly, less expensive and protects the habitats that ensure security and conservation for plants and animal life (Yadav et al., 2018).
Crop production in dry lad areas is mainly dependent on precipitation. The conventional tillage (CT) practiced by most farmers is to leave soil bare after harvesting the crops until planting of the next crop in dry land regions of the USA, China and Canada. In dry land agriculture farming system, conventional tillage with the use of moldboard plough is inefficient to conserve soil moisture during fallow period (Cruse et al., 1982; Dao, 1993). The soil becomes denser as a result of CT and forms a hardpan below the plough layer that impedes air and water flow, stunts root growth and eventually lowers crop production. Furthermore, wind erosion and soil deterioration are exacerbated by little precipitation (200 mm per year) and finely pulverized top soil brought on by repetitive ploughing.
Conservation tillage is referred to any tillage method which is practiced to minimize soil and water loss (Benites et al. 1998). With this classification, many practices are considered measures of conservation tillage, including shallow top and sub-soil tillage (ST), reduced tillage (RT) and no-tillage (NT) (Rasmussen, 1999; Lampurlanés et al., 2002; Wang et al., 2003). Conservation tillage systems (NT, RT and ST) have been introduced as alternatives to conventional tillage systems (Schillinger, 2001). Conservation tillage is advised as a crucial step in dry land farming to reduce the deterioration of soil physical and chemical properties and boost the water usage efficiency of crops (Huang et al., 2008). Since tillage has an impact on root growth in the sub soil, the development and dispersion of roots in the soil profile is crucial for plant’s ability to absorb water and nutrients (Godwin, 1990). However, tillage plays the most important role in soil-plant system such as continued use of conventional tillage method creates hard pan in soil that may damage the root proliferation below the plough layer (Maurya, 1988; Gill and Aulakh, 1990).
Several elements are taken into consideration about how soil behaves when NT is applied. These elements include the characteristics of soil, management history of land, weather and the type and intensity of tillage applied (Mahboubi et al., 1993). Reduced tillage directs to higher soil water content because it promotes soil penetration and decrease surface runoff and evaporation (Zhai et al., 1990). Moreover, conservation tillage can boost crop yield, lower the operational costs and have positive economic effects (O’Leary and Connor, 1997; Gicheru et al., 2004; Fabrizzi et al., 2005). However, Taa et al. (2004) found that the yield of no-till wheat can occasionally be lower compared to conventionally grown wheat such as Lampurlanés et al. (2002) described that crop productivity and water use efficiency were not affected by the type of tillage system.
Wheat (Triticum aestivum L.) is among the most important cereal crops (Adil et al., 2022; Bukhari et al., 2021; Bruning et al., 2020). It is accounted for 40% of China’s food grains and is cultivated on 4.3 million hectares of land on the Loess Plateau (Tong et al., 2003). It is planted on more than 2.2 million acres in the interior Pacific Northwest of the United States (Schillinger and Papendick, 2008). A wild grass in central Mexico gave rise to maize (Zea mays ) around 7000 years ago (Ranum et al., 2014). It is cultivated all over the world and has an energy density of 365 Kcal/100g. Maize comprises roughly 72% starch, 10% protein and 4% fat. However, the USA, China and Brazil are the top three maize-producing countries in the world such as these countries produce on an average of 563 of the 717 million metric tons of maize per year (Ranum et al., 2014). It is generally believed that in the nutrient deficient environment, water is the major yield limiting factor in dry areas (French and Schultz, 1984). There is an even indication that the excessive rainfall may actually reduce crop yields in dry land agriculture systems (Mason and Fischer, 1986). Moreover, inconsistent crop yields were obtained by different tillage systems (Su et al., 2007).
So, there is a need to check the yield difference of these two most important crops among different tillage methods around the globe. We hypothesized that (1) conservation tillage methods would have an overall positive effect on soil and plant parameters in both cropping systems; (2) such effect will differ between winter wheat and spring maize and/or within conservation tillage methods; and (3) edaphic and climatic conditions of several regions will modify the effect of conservation tillage methods on soil and plant parameters.
Materials and Methods