Deficit irrigation and fertilization strategies to improve soil quality and alfalfa yield in arid and semi-arid areas of northern China

Qianmin Jia; Muhammad Kamran; Shahzad Ali; Lefeng Sun; Peng Zhang; Xiaolong Ren; Zhikuan Jia

doi:10.7717/peerj.4410

Deficit irrigation and fertilization strategies to improve soil quality and alfalfa yield in arid and semi-arid areas of northern China

PeerJ. 2018 Feb 21:6:e4410. doi: 10.7717/peerj.4410. eCollection 2018.

Authors

Qianmin Jia^{1

2

3}, Muhammad Kamran^{1

2

4}, Shahzad Ali^{1

2

4}, Lefeng Sun^{1

2

4}, Peng Zhang^{1

2

4}, Xiaolong Ren^{1

2

4}, Zhikuan Jia^{1

2

4}

Affiliations

¹ Northwest A&F University, Institute of Water Saving Agriculture in Arid Areas of China, Yangling, Shaanxi, China.
² Northwest A&F University, Key Laboratory of Crop Physi-ecology and Tillage Science in North-western Loess Plateau, Ministry of Agriculture, Yangling, Shaanxi, China.
³ Northwest A&F University, College of Forestry, Yangling, Shaanxi, China.
⁴ Northwest A&F University, College of Agronomy, Yangling, Shaanxi, China.

Abstract

Background: In the arid and semi-arid areas of northern China, overexploitation of fertilizers and extensive irrigation with brackish groundwater have led to soil degradation and large areas of farmland have been abandoned. In order to improve the soil quality of abandoned farmland and make reasonable use of brackish groundwater, we conducted field trials in 2013 and 2014.

Methods: In our study, we used three fertilization modes (CF, chemical fertilizer; OM, organic manure and chemical fertilizer; NF, no fertilizer) and three deficit irrigation levels (I₀: 0 mm; I₇₅: 75 mm; I₁₅₀: 150 mm).

Results: The results showed that the activities of soil urease, alkaline phosphatase, invertase, catalase, and dehydrogenase in the OM treatment were significantly improved compared with those in the CF and NF treatments under the three deficit irrigation levels. Compared with NF, the OM treatment significantly increased soil organic carbon (SOC), water-soluble carbon (WSC), total nitrogen, microbial biomass carbon and nitrogen (MBC and MBN), and soil respiration rate, and significantly decreased soil C:N and MBC:MBN ratios and the metabolic quotient, thus improving the soil quality of abandoned farmland. Furthermore, the OM treatment increased alfalfa plant height, leaf area index, leaf chlorophyll content, and biomass yield. Under the CF and OM fertilization modes, the activities of urease and catalase in I₁₅₀ were significantly higher than those in I₀, whereas irrigating without fertilizer did not significantly increase the activity of these two enzymes. Regardless of fertilization, alkaline phosphatase activity increased with an increase in irrigation amount, whereas invertase activity decreased.

Discussion: The results showed that deficit irrigation with brackish groundwater under the OM treatment can improve soil quality. Over the two years of the study, maximum SOC, total nitrogen, WSC, MBC, and MBN were observed under the OM-I₁₅₀ treatment, and the alfalfa biomass yield of this treatment was also significantly higher than that of the OM-I₀ treatment. Therefore, the OM-I₁₅₀ treatment could be used as a suitable measure not only to improve the quality of abandoned farmland soil but also to increase the alfalfa biomass yield in arid and semi-arid areas of northern China.

Keywords: Deficit irrigation; Microbial biomass; Soil enzyme; Soil organic carbon; Soil respiration rate.

Grants and funding

This work was supported by the China Support Programs (2012BAD09B03 and 2015BAD22B02) for Dry-land Farming in the twelfth 5-year plan period, the National High-Tech Research and Development Programs of China (“863 Program”) for the twelfth 5-Year Plan (2013AA102902), the Program of Introducing Talents of Discipline to Universities (No. B12007), and the China Postdoctoral Science Foundation funded project (2016M602870). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.