Swine manure application enriches the soil food web in corn and soybean production.

Zane J Grabau,Yong Bao,Senyu Chen,Jeffrey A Vetsch

doi:10.21307/jofnem-2019-014

Abstract

Strategies for managing plant-parasitic nematodes while promoting soil quality are needed in corn (Zea mays) and soybean (Glycine max) cropping systems. Therefore, a series of two-year experiments were conducted in Minnesota to determine the simple and interactive effects of manure or conventional fertilizer and short-term crop rotation on the nematode community, a sensitive indicator of soil ecology. The two-year crop sequences were Sus-Sus, Res-Sus, and Corn-Sus, where Sus and Res are soybean susceptible and resistant to Heterodera glycines (soybean cyst nematode: SCN), respectively. The fertilizer treatments were liquid swine manure, conventional phosphorus (P)-potassium (K) fertilizer, and no fertilizer. Crop sequence and fertilizer choice had individual main effects, but did not have an interactive effect on the nematode community. Swine manure affected the nematode community in ways that conventional PK fertilizer or no fertilizer did not, substantially enhancing populations of bacterivores in colonizer-persister group 1, which are extreme enrichment opportunists. Manure application did not affect other groups of free-living nematodes and decreased nematode community diversity. Conventional PK fertilizer did not influence the nematode community compared with untreated control. The effects of short-term crop sequences were much less pronounced and consistent than manure application, but corn altered the environment to favor fungivores while soybean increased bacterivore abundances.

Highlights

In the United States, corn and soybean are among the most important crops, comprising 36.0 and 36.2 million hectares, respectively, in 2018, which was 55.5% of total area planted to principal crops (NASS-USDA, 2018)
Reported studies in the region have investigated the impact of swine manure or conventional synthetic or mined nitrogen (N) – phosphorus (P) – potassium (K) – sulfur (S) fertilizer and nematicide application in combination with conventional or conservation tillage (Grabau et al, 2018) as well as long-term corn and soybean cyst nematode (SCN)-susceptible soybean crop sequences crossed with nematicide application on the nematode community (Grabau and Chen, 2016c)
This trend was driven primarily by c-p1 bacterivores as manure consistently increased abundances of this group compared with no fertilizer or chemical fertilizers (Fig. 1), but generally did not affect c-p2 bacterivores (Fig. 2) and there were very few bacterivores belonging to any other guild

Summary

Introduction

In the United States, corn and soybean are among the most important crops, comprising 36.0 and 36.2 million hectares, respectively, in 2018, which was 55.5% of total area planted to principal crops (NASS-USDA, 2018). The influence of fertilizers on soil ecology in corn-soybean crop rotation systems is of interest because rotation with corn or SCN-resistant soybean is the main SCN management strategy and soil community response to fertilizers may vary by crop Both nutrient uptake (Halvorson and Schlegel, 2012) and root exudate profiles (Wagner and Broder, 1993) differ between corn and soybean, so nutrients and compounds available to the soil nematode and microbial community may vary by crop. Plant residue volume and nutrient content, soil moisture, and other factors vary between corn and soybean (Wagner and Broder, 1993; Nickel et al, 1995; Pedersen and Lauer, 2004; Halvorson and Schlegel, 2012) which may influence soil community responses to fertilizer application. Specific hypotheses included: (i) manure application provides carbon sources to the nematode community that conventional PK fertilizer or no fertilizer does not resulting in an enrichment of the nematode community; (ii) short-term crop sequences do not influence the soil environment enough to impact the nematode community within the two-year scope of this study; and (iii) short-term crop sequences and fertilizer application have an interaction effect on the nematode community, that soybean cropping enhances the enrichment effects of swine manure

Objectives

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Results

Conclusion