Effects of strip cropping with reducing row spacing and super absorbent polymer on yield and water productivity of oat (Avena sativa L.) under drip irrigation in Inner Mongolia, China

Abstract With the serious shortage of water resources and the development of water-saving agriculture, the application of drip irrigation has been paid more and more attention. But there was lack of oat planting methods suitable for drip irrigation, currently. In order to establish an efficient oat planting method for drip irrigation, a study was conducted at Agriculture and Forestry Sciences of Ulanqab, Inner Mongolia during the season (2019–2020) to evaluate the effect of strip cropping with reducing row spacing and super absorbent polymer on the yield and water use efficiency of oat. To conduct the field trials, a split plot system in three replications was established. Three planting patterns were in the main plots, including conventional cropping with 20 cm equal row spacing (PA), strip cropping with the 15 cm row spacing (PB) and strip cropping with the 10 cm row spacing (PC), and two super absorbent polymer levels were in the subplots, including 22.5 kg ha−2 (Y) and 0 (N). The results showed that, compared with PA, PB and PC both decreased the irrigation volumes by 4.5–18.4 mm, and the irrigation volumes of PB was lower than that of PC. When super absorbent polymers were applied, compared with PA, PB significantly increased grain yield and above-ground biomass, but PC had the opposite effects. The grain yield and above-ground biomass of PB significantly increased by 16.65% and 7.31% on average in two years, respectively. And the increasing of grain yield was attributed by the significant increasing of pike number and kernel number per spike. But when super absorbent polymers were not applied, PB had no significant effects on grain yield and above-ground biomass. PB also had the significant effects on regulating water use of oats weather or not super absorbent polymers were applied, it significantly increased the precipitation ratio by 2.64% (PBY) and 2.13% (PBN) and decreased irrigation ration by 3.32% (PBY) and 5.28% (PBN) on average in two years. Although PB and PC both decreased the total evapotranspiration, but PB increased WUE and PC deceased WUE. The WUE of PB increased by 19.70% (PBY) and 9.87% (PBN) on average in two years. Also PB had the highest economic benefits in all treatments. In conclusion, a drip irrigation oat planting pattern was proposed, which the row spacing is 15 cm, adjusted the equal row spacing planting to 8-row strip planting, with a belt spacing of 30 cm, combined with the application of 22.5 kg ha−2 applying super absorbent polymers. And this oat planting pattern is a viable strategy to improve oat productivity.