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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (1): 107-117.DOI: 10.11686/cyxb2021216

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Combined ploughing and tilling to improve degraded alfalfa (Medicago sativa) stands in a semi-arid region

Bin WANG1(), Man-you LI1, Xin-pan WANG1, Xiu DONG2, Jun-bao PANG3, Jian LAN1()   

  1. 1.College of Agriculture,Ningxia University,Yinchuan 750021,China
    2.College of Grassland Agriculture Science and Technology,Lanzhou University,Lanzhou 730020,China
    3.Ningxia Longde County Livestock Technology Extension Service Center,Guyuan 756000,China
  • Received:2021-05-25 Revised:2021-07-05 Online:2021-12-01 Published:2021-12-01
  • Contact: Jian LAN

Abstract:

Degraded alfalfa (Medicago sativa) stands in semi-arid regions have a low forage yield and poor forage quality, but may be improved by management methods such subsoiling. We conducted a 3-year field experiment with a single factor randomized block design to study the restorative effects on soil physical and chemical properties of subsoiling combined with shallow rotary tilling: plowing to 30 cm+tilling to 5 cm (S1Q1), plowing to 30 cm+tilling to 10 cm (S1Q2), plowing to 40 cm+tilling to 5 cm (S2Q1), plowing to 40 cm+tilling to 10 cm (S2Q2), plowing to 50 cm+tilling to 5 cm (S3Q1), plowing to 50 cm+tilling to 10 cm (S3Q2) and control (CK). Production performance and forage quality of degraded alfalfa grassland were determined, and a principal component analysis (PCA) was used to evaluate the improvement effects of the treatments. It was found that plowing with shallow rotary tilling reduced the soil bulk density, increased soil porosity, and led to significant increases in the plant height, branch number, and leaf∶stem ratio of alfalfa. Among the treatments, S2Q1 reduced the soil bulk density in the 0-40 cm soil layer, and S2Q2 increased the branch number, hay yield, and crude protein content in alfalfa, and reduced the neutral and acid detergent fiber contents. The results of the PCA indicated that the treatments had larger effects on alfalfa hay yield, leaf∶stem ratio, and crude protein content, and smaller effects on the forage relative feeding value and neutral detergent fiber content. The S2Q2 treatment with deep loosening by plowing and shallow tilling led to a high alfalfa hay yield (6505.44 kg·ha-1) and crude protein content (20.74%). The treatments were ranked, from largest effects on the multivariate performance score for alfalfa forage to smallest, as follows: S2Q2,S1Q2,S2Q1,S3Q2,S1Q1,S3Q1,CK. Therefore, plowing to 40 cm+tilling to 10 cm was found to be the most effective treatment for improving degraded alfalfa stands in this semi-arid area.

Key words: plowing and shallow rotary cultivation, degraded alfalfa stands, yield, quality