Increasing maize production and preventing water deficits in semi-arid areas: A study matching fertilization with regional precipitation under mulch planting

Highlights

• Full-film mulching maintained the water balance better than half-film mulching.

• Full-film mulching was also better at promoting maize production within four years.

• We demonstrated optimal matching of fertilization and regional precipitation.

• Critical water deficit values were established as a warning system.

Abstract

Maize production in semi-arid areas is increasingly at risk due to limited and uneven precipitation, and is further constrained by unvalidated nutrition management practices. Matching fertilization levels to regional precipitation, however, can ensure sustainable water use and crop productivity. From 2014–2017, a 4-year field experiment was performed to evaluate the effects of fertilization at five levels (N 0+P₂O₅ 0 kg ha⁻¹, N 117+ P₂O₅ 59 kg ha⁻¹, N 173+ P₂O₅ 87 kg ha⁻¹, N 229+ P₂O₅115 kg ha⁻¹, and N 285+ P₂O₅143 kg ha⁻¹) under two typical ridge-furrow mulch plantings (full plastic film mulching, RFF; half plastic film mulching, RFH) on soil water storage, maize yield performance, and water use efficiency (WUE) in a rainfed semi-arid region of the Loess Plateau, China (430 mm and 8 °C in average annual precipitation and air temperature respectively). Fertilization promoted evapotranspiration (ET) and increased maize grain yields by 97.9–141.8 % and WUE by 94.4–122.5 % under both mulch plantings. However, soil water storage at sowing (SWS_s) was reduced from 575.5 mm in 2014 to 358.8–500.0 mm under RFF and to 327.4–460.3 mm under RFH in 2017, with the water imbalance exacerbated by the increase in fertilization level. This study reveals that coordinating fertilization with SWS_s to optimize ET can promote sustainable water use and maize yields, and thus fertilization at N 180.9+P₂O₅ 90.5 kg ha⁻¹ is recommended under RFF, while that at N 120.1+P₂O₅ 60.5 kg ha⁻¹ under RFH in the semi-arid rain-fed agricultural areas. Although RFF can maintain sustainable water use at higher fertilization level and achieve higher grain yields and WUE compared with RFH, RFH performances a water-saving potential of 60 mm compared with RFF, as evidence shows that the available water (SWS_s plus precipitation) to ensure sustainable use of water requires 370–760 mm under RFH, but 440–825 mm under RFF according to a dynamic warning system to avoid water deficit.

Introduction

Maize (Zea mays L.) is an important cereal crop that is widely used as food for humans and livestock, as well as raw material for industrial production. In 2014, 2.2 × 10⁸ ha of maize were planted around the world, yielding 1.2 × 10¹² kg of grain (FAO, 2015). Global demand for maize grain is expected to double by 2050 due to population growth and the increasing demand for industrial raw materials (CIMMYT, 2011). To minimize the need for additional arable land, total grain production must be increased through intensification of productivity, that is, increasing crop yields per unit of cultivated land (Gu et al., 2019; Teixeira et al., 2014). However, maize production is increasingly at risk due to global climate change and unpredictability of precipitation patterns. Especially at high risk are the more than half of maize growing areas that are under dryland conditions (FAO, 2015). For example, maize yields are highly uncertain in semi-arid areas of the Loess Plateau, China, because of rare and uneven precipitation, as well as the use of unvalidated nutrition management practices.

The Loess Plateau (32–41 °N, 107–114 °E) in northwest China is a typical arid and semi-arid region where poverty is endemic. The Plateau comprises 341 counties, with a total area of 648,700 km² and total cultivated land area of approximately 150,000 km². Because of its lack of vegetation, loose soil, and large variation in precipitation (2–5 times difference between wet and dry years), this region has seriously eroded soil and is one of the most fragile ecological environments in the world (Deng et al., 2006; Li et al., 2009b). The average annual precipitation in this region is only about 460 mm, while the water surface evaporation capacity is up to 1500–2000 mm. Thus, groundwater and surface water available for farmland irrigation are scarce (Dong et al., 2019). The shortage of water resources is the most critical factor restricting the crop yields in the Loess Plateau region. In addition, 60 % of the annual precipitation in this region occurs from July to September (summer to autumn) in the form of heavy rains or rainstorms. As a result, spring droughts are common, which impedes seed germination and seedling growth and can lead to crop failures.

Researchers have been exploring efficient water use technologies for semi-arid areas (Gan et al., 2013; Chai et al., 2014), and showed that ridge-furrow construction combined with plastic film mulch planting is an efficient approach to dryland agriculture production. This practice consists of alternating ridges and furrows, with ridges covered in transparent plastic film (Mo et al., 2016; Zhang et al., 2019; Zhao et al., 2014). This technology improves the efficiency of rain collection by coupling ridge runoff and furrow precipitation, and creates an impermeable barrier to inhibit the loss of water and heat from the soil surface (Han et al., 2004; Wang et al., 2008). This significantly improves the hydrothermal environment of crops, promoting their growth and development and improving yields and resource utilization efficiency (Chai et al., 2014; Gan et al., 2013). At present, the two ridge-furrow mulching planting methods that have been studied and applied most often are ridge-furrow construction with full plastic film mulching (RFF, Fig. 1a) and ridge-furrow construction with half plastic film mulching (RFH, Fig. 1b) (Zhang et al., 2019; Zhao et al., 2014).

Fertilization contributes up to 40 % of crop yields, making this one of the most important agricultural production measures (Ju et al., 2009; Li et al., 2009a). Since the 1990s, China has become the largest consumer of fertilizers (i.e., nitrogen, phosphorus, potassium, and compound fertilizers) in the world, with total consumption increasing from 26 million tons in 1989 to about 60 million tons now. However, in many semi-arid areas, including the Loess Plateau, unvalidated nutrient (both excessive and insufficient) management, in addition to water availability, limits crop productivity (Bu et al., 2014; Li et al., 2009a; Liu et al., 2014). Within a certain range, fertilizers can promote crop growth and water use, but fertilization in excess of this range cannot significantly improve crop yields, disrupting a fragile water balance and introducing further uncertainty in agricultural production (Liu et al., 2014). Due to the extensive application of mulch planting, water and heat availability in some semi-arid areas, including the Loess Plateau, has changed (Bu et al., 2013; Liu et al., 2010). Therefore, matching fertilization management techniques with new water resource patterns in response to mulch planting is the key to ensure sustainable water use and crop productivity. Without this attention, agricultural water may be depleted and regional food security will continue to deteriorate.

Many studies have shown that soil water storage at sowing is an important parameter in agricultural production of dryland wheat (Li et al., 2004; Meng et al., 2012). Sufficient soil water can directly alleviate water stress to promote seed germination and emergence (Li et al., 2004; Meng et al., 2012), mitigate extreme changes in soil temperature to prevent crop damage from freezes (Liu et al., 2016), and promote dissolution and diffusion of nutrients to increase their availability(Li et al., 2009b). Each of these factors can help stimulate crop productivity and reduce the uncertainty associated with the amount of precipitation after sowing on the growth of wheat (Dong et al., 2019; Meng et al., 2012). However, current studies rarely focus on soil water at sowing with maize (especially under mulch planting) because maize growth is generally believed to coincide with the hydrothermal peak in summer. As patterns of agricultural hydrothermal resources change, studies on how to match fertilization amount with regional precipitation under high-efficiency ridge-furrow mulch planting is of vital importance to improve maize production in the Loess Plateau, as well as to ensure regional water and food security. The objectives of this study were to: 1) study the effects of fertilization and precipitation on soil water dynamics (especially at the time seeds are sown), maize yields, and water use efficiency (WUE) with common mulch planting methods; 2) clarify the effective strategy that matching fertilizer application with regional precipitation to achieve sustainable water use and crop productivity in semi-arid areas. 3) develop early warning schemes to prevent water deficit for maize production, and to compare the water use potential between RFF and RFH that the two typical mulching methods in semi-arid areas.