Root Development of Transplanted Cotton and Simulation of Soil Water Movement under Different Irrigation Methods

Hao Zhang,Wanning Wang,Yang Gao,Hao Liu,Jingsheng Sun,Chitao Sun,Xuewen Gong

doi:10.3390/w9070503

Hao Zhang, Wanning Wang + Show 5 more

Open Access

https://doi.org/10.3390/w9070503

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Abstract

Winter wheat and cotton are the main crops grown on the North China Plain (NCP). Cotton is often transplanted after the winter wheat harvest to solve the competition for cultivated land between winter wheat and cotton, and to ensure that both crops can be harvested on the NCP. However, the root system of transplanted cotton is distorted due to the restrictions of the seedling aperture disk before transplanting. Therefore, the investigation of the deformed root distribution and water uptake in transplanted cotton is essential for simulating soil water movement under different irrigation methods. Thus, a field experiment and a simulation study were conducted during 2013–2015 to explore the deformed roots of transplanted cotton and soil water movement using border irrigation (BI) and surface drip irrigation (SDI). The results showed that SDI was conducive to root growth in the shallow root zone (0–30 cm), and that BI was conducive to root growth in the deeper root zone (below 30 cm). SDI is well suited for producing the optimal soil water distribution pattern for the deformed root system of transplanted cotton, and the root system was more developed under SDI than under BI. Comparisons between experimental data and model simulations showed that the HYDRUS-2D model described the soil water content (SWC) under different irrigation methods well, with root mean square errors (RMSEs) of 0.023 and 0.029 cm3 cm−3 and model efficiencies (EFs) of 0.68 and 0.59 for BI and SDI, respectively. Our findings will be very useful for designing an optimal irrigation plan for BI and SDI in transplanted cotton fields, and for promoting the wider use of this planting pattern for cotton transplantation.

Highlights

The North China Plain (NCP) is one of the most important cotton and grain production regions in China [1,2]
The spatial distribution of root length density (RLD) at soil depths of 0–70 cm in the bloom and boll-forming stage of transplanted cotton is shown in Table 5 and Figure 6
Roots are closely related to soil water movement; investigating the deformed root distribution of transplanted cotton is essential for simulating soil water movement under different irrigation methods

Summary

Introduction

The North China Plain (NCP) is one of the most important cotton and grain production regions in China [1,2]. The competition between cotton and grain crops for cultivated land has become increasingly serious. The planting patterns used for cotton and grain must be changed to ensure adequate supplies of cotton and grain. Transplantation of cotton after the winter wheat harvest has gradually become a more common planting pattern on the NCP [2]. This pattern can improve cultivated land use efficiency and allow both cotton and grain crops to be harvested [2,3]. Compared to the traditional winter wheat–cotton intercropping system, transplantation of cotton after winter wheat harvest can increase the winter wheat planting area by 40%

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