Simulation of Soil Organic Carbon Effects on Long-Term Winter Wheat (Triticum aestivum) Production Under Varying Fertilizer Inputs.

Bhim B Ghaley,Yubaraj K Karki,Jørgen E Olesen,Pete Smith,Henk Wösten,Peter Kuikman,Jagadeesh Yeluripati,Christen D Børgesen,Jan-Peter Lesschen,Marco Bindi,Sanmohan Baby,Kirsten Schelde,Roberto Ferrise,John R Porter

doi:10.3389/fpls.2018.01158

Abstract

Soil organic carbon (SOC) has a vital role to enhance agricultural productivity and for mitigation of climate change. To quantify SOC effects on productivity, process models serve as a robust tool to keep track of multiple plant and soil factors and their interactions affecting SOC dynamics. We used soil-plant-atmospheric model viz. DAISY, to assess effects of SOC on nitrogen (N) supply and plant available water (PAW) under varying N fertilizer rates in winter wheat (Triticum aestivum) in Denmark. The study objective was assessment of SOC effects on winter wheat grain and aboveground biomass accumulation at three SOC levels (low: 0.7% SOC; reference: 1.3% SOC; and high: 2% SOC) with five nitrogen rates (0–200 kg N ha-1) and PAW at low, reference, and high SOC levels. The three SOC levels had significant effects on grain yields and aboveground biomass accumulation at only 0–100 kg N ha-1 and the SOC effects decreased with increasing N rates until no effects at 150–200 kg N ha-1. PAW had significant positive correlation with SOC content, with high SOC retaining higher PAW compared to low and reference SOC. The mean PAW and SOC correlation was given by PAW% = 1.0073 × SOC% + 15.641. For the 0.7–2% SOC range, the PAW increase was small with no significant effects on grain yields and aboveground biomass accumulation. The higher winter wheat grain and aboveground biomass was attributed to higher N supply in N deficient wheat production system. Our study suggested that building SOC enhances agronomic productivity at only 0–100 kg N ha-1. Maintenance of SOC stock will require regular replenishment of SOC, to compensate for the mineralization process degrading SOC over time. Hence, management can maximize realization of SOC benefits by building up SOC and maintaining N rates in the range 0–100 kg N ha-1, to reduce the off-farm N losses depending on the environmental zones, land use and the production system.

Highlights

Soil organic carbon (SOC) supports multiple soil functions determining soil physical, chemical and biological quality parameters (Reeves, 1997; Pan et al, 2009) contributing to the productive capacity of soils for food, fodder, and energy production (Lal, 2004)
This provided the scientific rationale for using DAISY for simulation of grain yields and aboveground biomass accumulation at low, reference, and high SOC content under 0–200 kg N ha−1 treatments in this study
In similarity to our study, DAISY model had been used for simulation of crop grain yield and aboveground biomass accumulation in several model comparison exercises (Dewilligen, 1991; Vereecken et al, 1991; Diekkrüger et al, 1995) and validation of crop yield in winter wheat in three sites in the Netherlands (Hansen et al, 1991)

Summary

Introduction

Soil organic carbon (SOC) supports multiple soil functions determining soil physical, chemical and biological quality parameters (Reeves, 1997; Pan et al, 2009) contributing to the productive capacity of soils for food, fodder, and energy production (Lal, 2004). The other effects of increased SOC content are decrease in the bulk density (Chen et al, 2017; Palmer et al, 2017; Minasny and McBratney, 2018) and small increase in volumetric water holding capacity (Rawls et al, 2003). Due to these multiple effects, there is a great interest to quantify SOC effects in agro-ecosystems. Quantification of SOC effects on N supply, soil water retention and crop productivity under varying fertility production system provides a science-based evidence of SOC benefits for making management decisions by farmers

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Conclusion