Soil Extracellular Enzyme Activities and Uptake of N by Oilseed Rape Depending on Fertilization and Seaweed Biostimulant Application

Anetta Siwik-Ziomek,Małgorzata Szczepanek

doi:10.3390/agronomy9090480

Abstract

The present study has aimed at enhancing the insufficient knowledge of functional soil enzymes properties influenced by inorganic fertilization and biostimulant application to increase the uptake of nitrogen affecting the winter oilseed rape yield. Field experiments were conducted in Poland (53° N, 18° E) in Alfisol (USDA). In this experiment, the NPK rates applied were as follows: high 180 N, 70 P and 160 K 132 N (kg ha−1) or low 144 N, 35 P and 66 K (kg ha−1); fertilization with elemental S 36 or 0 (kg ha−1); and the seaweed biostimulant Kelpak was applied or there was no such treatment. Due to low NPK fertilization rates, the activity of dehydrogenases, peroxidases, and catalase increased in subsistent generative development stages from flowering to ripening. At the ripening stage, the activity of these enzymes, as well as nitroreductase activity, were inhibited by high NPK fertilizer rates. The seaweed biostimulant application and S fertilization increased N accumulation in plants of oilseed rape in generative development, by 16% and 13%, respectively, as compared with the lack of these treatments. The application of S increased the uptake of nitrogen in shoots and in whole oilseed rape plants only after application of higher rates of NPK.

Highlights

Nitrogen is one of the key sources of nutrients applied into soil to increase the efficiency of agricultural crops, it can trigger environmental protection problems when it is applied inadequately [1,2,3]
The activities of enzymes changed during the vegetation period of winter rape and depended on the mineral fertilization level and biostimulant application (Table 2)
At the successive rape development stage, the activities decreased by 63% for DH and 60% for NR and at the ripening stage, it decreased by 47% and 70%, respectively

Summary

Introduction

Nitrogen is one of the key sources of nutrients applied into soil to increase the efficiency of agricultural crops, it can trigger environmental protection problems when it is applied inadequately [1,2,3]. Soil enzymes take part in the circulation of biogenic elements C, N, P, and S [4], which is of great importance in terms of ecology as the activity of microorganisms and the enzymes they secrete provide the cycle of elements to nature [4,5] and convert the substances they contain into forms available to organisms. Catalase activity was used to characterize soil microbial activities [10]. Peroxidases mediate biogeochemical processes in soils, including microbial acquisition of carbon and nitrogen, lignin degradation and carbon

Objectives

Methods

Results

Discussion

Conclusion