4.3. Implications
Since the initiation of the Grain for Green project in 1999, extensive
commercial plantations of jujube, apple (Malus domestica ), walnut
(Juglans regia ), and peach (Prunus persica ), among others,
have been planted on the Loess Plateau, with the aim of delivering
ecological and economic benefits (Gao et al., 2014). For example, the
area of planted apple trees reached 130 million ha by 2017 (Gao et al.,
under review). On the Loess Plateau, these commercial plantations are
primarily run by smallholder farmers. Because of the complex topography
and high cost of irrigation, most of these plantations are rainfed (Gao
et al., 2018b). Therefore, efficient use of rainwater and improved SWS
are critical to their success. Our results indicate that, compared to
traditional hillslopes and terraces alone, the combination of terracing
and mulching clearly increases SWS, enhances deep-layer water use and
transpiration, and results in higher mid-day leaf water potential,
particularly during drought periods. Therefore, the combination of
terraces and mulches is strongly recommended for use in commercial
plantations on the Loess Plateau, and potentially also in drylands
worldwide, thus helping to deliver Sustainable Development Goals (United
Nations, 2015).