Organic inputs, tillage and rotation practices influence soil health and suppressiveness to soilborne pests and pathogens of ginger

Abstract

A field experiment was established in which an amendment of poultry manure and sawdust (200 t/ha) was incorporated into some plots but not others and then a permanent pasture or a sequence of biomass-producing crops was grown with and without tillage, with all biomass being returned to the soil. After 4 years, soil C levels were highest in amended plots, particularly those that had been cropped using minimum tillage, and lowest in nonamended and fallowed plots, regardless of how they had been tilled. When ginger was planted, symphylans caused severe damage to all treatments, indicating that cropping, tillage and organic matter management practices commonly used to improve soil health are not necessarily effective for all crops or soils. During the rotational phase of the experiment, the development of suppressiveness to three key pathogens of ginger was monitored using bioassays. Results for root-knot nematode (Meloidogyne javanica) indicated that for the first 2 years, amended soil was more suppressive than non-amended soil from the same cropping and tillage treatment, whereas under pasture, the amendment only enhanced suppressiveness in the first year. Suppressiveness was generally associated with higher C levels and enhanced biological activity (as measured by the rate of fluorescein diacetate (FDA) hydrolysis and numbers of free-living nematodes). Reduced tillage also enhanced suppressiveness, as gall ratings and egg counts in the second and third years were usually significantly lower in cropped soils under minimum rather than conventional tillage. Additionally, soil that was not disturbed during the process of setting up bioassays was more suppressive than soil which had been gently mixed by hand. Results of bioassays with Fusarium oxysporum f. sp. zingiberi were too inconsistent to draw firm conclusions, but the severity of fusarium yellows was generally higher in fumigated fallow soil than in other treatments, with soil management practices having little impact on disease severity. With regard to Pythium myriotylum, biological factors capable of reducing rhizome rot were present, but were not effective enough to suppress the disease under environmental conditions that were ideal for disease development.

Cover crops to increase soil microbial diversity and mitigate decline in perennial agriculture. A review

“…When litter is left on the soil surface, as in a no-till system, saprotrophic microbial communities become more structured due to the stratification of different nutrients through the soil (Holland and Coleman 1987). This heterogeneity of resources leads to increased microbial diversity found in no-till systems (Govaerts et al 2007) and could increase the ability of soils to suppress disease (Stirling et al 2012), but this has not been investigated specifically in a cover cropped perennial system.…”

Dynamics of a Soil Fungal Community in a Three-Year Green Garlic/Cucumber Crop Rotation System in Northwest China

“…The principal component analysis (PCA) of the fungal community, as shown in Figure 3, also elucidated that significant variations occurred between the green garlic-and cucumber-planted soils among the individual samples during the whole experiment duration, as well as between the treatments with green garlic and cucumber mono-cropping. Agricultural soil management practices and cropping systems can directly affect the fungal community composition, as reported by numerous authors [49,[65][66][67][68]. Continuous cropping under a protected cultivation system is becoming an unrealistic approach, which considerably affects the biomass and activity of soil microorganisms unless the cropping pattern is modified [44,69,70].…”

Diseases infecting ginger (Zingiber officinale Roscoe): A review

“…Smith et al (2011) found greatest (74.2 t/ha) rhizome yield and minimal (7.0%) losses to pathogens in the pasture lay that had been cultivated prior to ginger planting. Stirling et al (2012) reported that organic inputs, tillage and rotation practices did not influence yellows disease. Results of bioassays were too inconsistent to draw firm conclusions, even soil management practices had little impact on disease severity.…”

“…Amendment of organic matter, including poultry manure and sawdust (200 t/ha) enriched diversity of soil microbial communities in these ginger fields (Rames et al, 2013). These practices also increased soil carbon levels and water infiltration rates which supported growth and yield of ginger and helped to suppress soft rot on ginger (Smith et al, 2011;Stirling et al, 2012). Neem seed cake was found most effective with least average mortality of 20.3 per cent followed by poultry manure (22.7 %) while evaluating organic and inorganic amendments to manage rhizome rot in pot culture studies (Kadam et al, 2014).…”