Soil pH, nitrogen, phosphatase and urease activities in response to cover crop species, termination stage and termination method

Adewole Tomiwa Adetunji; Bongani Ncube; Andre Harold Meyer; Olatunde Stephen Olatunji; Reckson Mulidzi; Francis Bayo Lewu

doi:10.1016/j.heliyon.2021.e05980

Soil pH, nitrogen, phosphatase and urease activities in response to cover crop species, termination stage and termination method

Heliyon. 2021 Jan 24;7(1):e05980. doi: 10.1016/j.heliyon.2021.e05980. eCollection 2021 Jan.

Authors

Adewole Tomiwa Adetunji¹, Bongani Ncube², Andre Harold Meyer³, Olatunde Stephen Olatunji⁴, Reckson Mulidzi³, Francis Bayo Lewu¹

Affiliations

¹ Department of Agriculture, Cape Peninsula University of Technology, Wellington 7655, Western Cape, South Africa.
² Centre for Water and Sanitation Research, Department of Civil Engineering, Cape Peninsula University of Technology, Bellville, 7535, Western Cape, South Africa.
³ ARC Infruitec -Nietvoorbij, Private Bag X5026, Stellenbosch 7599, South Africa.
⁴ School of Chemistry and Physics, College of Agriculture, Engineering and Science, University of KwaZulu-Natal, Westville, Durban 4000, South Africa.

Abstract

The best management options for cover cropping are largely unknown, including the growth patterns of cover crop (CC) species, optimum termination stages and termination methods. A greenhouse experiment was conducted to explore the following: (i) Effect of two termination stages (vegetative and flowering) on the chemical composition (N and C:N) of four CCs; (ii) Short-term impacts of living CCs and residues on soil pH, total N, urease and phosphatase activities at the two termination stages, and under two termination methods (slash and spray). Species tested as CCs were, vetch (Vicia dasycarpa L.), field pea (Pisum sativum L.), oats (Avena sativa L.), rye (Secale cereal L.) and a control (no CC). The experiment was set up in a randomized block design with three replications. Soil was sampled at kill and one year after CC kill. Delaying termination from vegetative till flowering stage decreased N in the tissue of P. sativum, A. sativa, V. dasycarpa and S. cereal by 59%, 65%, 44% and 56%, respectively, while their C:N ratios increased. Cover crop presence had no effect on soil pH. Living CCs had no significant effect on soil N concentration. The activities of urease and phosphatase were stimulated by all the living CC species. Unlike urease, all CC residues had a positive impact on phosphatase activity at one year. Only P. sativum and V. dasycarpa residues increased soil N concentration in the short-term. Compared to flowering, termination at vegetative stage improved soil N concentrations and phosphatase activity at both sampling times. Termination method had no effect on soil N, urease and phosphatase activity at one year. The significant interaction (P < 0.05) of sampling time, CC and termination stage effects on soil N concentration and phosphatase activity observed in this study indicates that these management approaches can optimize CC benefits and improve soil chemical and biological properties.

Keywords: Cover crop; Nitrogen; Phosphatase; Soil fertility; Urease.