Effects of Straw and Biochar Amendments on Grassland Productivity and Root Morphology

Tomasz Głąb,Wojciech Szewczyk,Monika Mierzwa-Hersztek,Krzysztof Gondek

doi:10.3390/agronomy10111794

Tomasz Głąb, Wojciech Szewczyk + Show 2 more

Open Access

https://doi.org/10.3390/agronomy10111794

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Abstract

The objective of this research was to determine the effect of straw and biochar amendment on the root system morphology and aboveground biomass of a red clover/grass mixture (Lolium. perenne L., Phleum pratense L., Festuca pratensis Huds., F. arundinacea Schreb., L. multiflorum L., L. westerwoldicum Breakw., Trifolium pratense L.). A grassland experiment was conducted from 2014 to 2018. Straw was collected from miscanthus (Miscanthus × giganteus), winter wheat (Triticum aestivum L.), and biochar was produced from the biomass of those species. The following treatments were applied: wheat straw at a rate of 5 t ha−1 (WS), miscanthus straw at a rate of 5 t ha−1 (MS), wheat biochar at a rate of 5 t ha−1 (WBH), wheat biochar at a rate of 2.25 t ha−1 (WBL), miscanthus biochar at a rate of 5 t ha−1 (MBH), and miscanthus biochar at a rate of 2.25 t ha−1 (MBL). A treatment with mineral fertilizer but without organic amendments (MCTR) was used, and a control treatment (CTR) without mineral fertilizer and without any amendments was also tested. The botanical composition and the aboveground yields were determined. The roots were sampled in 2018, and the root morphology parameters were determined using an image analysis system. The applied soil amendments resulted in increased root lengths, surface areas, volumes, and mean root diameters. There were no differences between the treatments with different feedstock types (miscanthus vs. wheat), materials (straw vs. biochar), or amendment rates (5 vs. 2.25 t ha−1). The resulting root system characteristics were reflected in the aboveground biomass productivity. The soil amendments, i.e., the straw and biochar, significantly increased the productivity in comparison to that of the control treatment. However, these differences were noticed only during the first and second cuts. Recommended practice in grassland management is to improve soil with straw. The conversion of straw into biochar does not provide a better effect on grassland productivity.

Highlights

Organic amendment is a well-known and common practice for providing nutrients to crops and conserving soil and water
The analysis of the data from the experimental trial with the red clover/grass mixture amended with straw and biochar produced from wheat and miscanthus revealed a positive effect on the root system and the aboveground productivity
Lower values of root:shoot ratio (RSR) resulted from the predominant percentage of the grass species in the botanical composition. The results of this five-year field experiment undertaken on a meadow red clover/grass mixture on loamy sand soil have demonstrated that straw and biochar amendments significantly affect aboveground parts of plants and their root system morphology

Summary

Introduction

Organic amendment is a well-known and common practice for providing nutrients to crops and conserving soil and water. The use of straw as an organic amendment is widely recommended in various conservation tillage systems [1]. Straw is usually used as a mulch after crop harvesting because of its beneficial effects on the soil physical, chemical, and biological properties. It reduces the soil bulk density and improves the soil structure and soil pore system [2]. According to Zhang et al [4], straw amendment increases the available nitrogen and phosphorus content in the upper soil layers and enhances the urease, phosphatase, and invertase activity levels in the lower soil layers. The incorporation of straw into soil increases crop biomass production [5]

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