Effect of conventional and organic orchard floor management practices on arbuscular mycorrhizal fungi in a ‘Cripp’s Pink’/M7 apple orchard soil
- Authors: Meyer, André H , Wooldridge, John , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444012 , vital:74178 , https://doi.org/10.1016/j.agee.2015.07.026
- Description: Arbuscular mycorrhizal (AM) fungi are key components of agricultural soil–plant systems, which may be affected by agricultural practices. In organically managed (ORG) orchards, nutrients are supplied in the form of compost, and weeds are suppressed with mulches, whereas synthetic fertilizers and herbicides are used for these respective purposes in conventional (CON) orchards. The effects of ORG and CON orchard floor management practices on native AM fungi in apple orchards were investigated in a randomized field trial. AM root colonization, spore abundance, infectivity potentials and soil glomalin contents were determined in the 0–30 cm soil depth interval, in tree rows, over consecutive seasons. Root colonization was higher in the ORG than the CON treatments, but intermediate where straw mulch was substituted for green work-row covers. Glomalin levels were not affected by the treatments. Root colonization by AM fungi increased with increasing soil pH, P, C, K, Zn, and Mn concentrations, but were suppressed by Cu. Colonization correlated positively with leaf P, Ca and Mg, and with stem circumference, but negatively with leaf N and yield. ORG orchard floor management practices therefore, promoted functional AM associations more effectively than CON practices.
- Full Text:
- Date Issued: 2015
Variation in urease and β-glucosidase activities with soil depth and root density in a ‘Cripp's Pink’/M7 apple orchard under conventional and organic management.
- Authors: Meyer, André H , Wooldridge, John , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444051 , vital:74181 , https://doi.org/10.1080/02571862.2015.1053155
- Description: The effects of conventional (CON; utilising synthetic fertiliser and herbicide) and organic (ORG; nutrients supplied in compost, weeds controlled with straw mulch) orchard floor management practices on depth-wise variation in urease and β-glucosidase activities in tree-row soils were compared in a Western Cape ‘Cripp's Pink’/M7 apple orchard. Urease and β-glucosidase activities were determined spectrophotometrically in soils from five depth intervals from the walls of trenches excavated across the tree rows after seven years of treatment application. Soil pH, organic carbon, nitrate (NO3 ) and ammonium (NH4 ) nitrogen were also determined, as was root density. Enzyme activities were higher in the ORG than the CON topsoils but did not differ significantly (p = 0.05) at depths >30 cm. The positive effects of the ORG treatments were attributed to the liming effect and carbon and nitrogen contributions of the compost. Urease and β-glucosidase activities correlated strongly. Activities of both enzymes correlated significantly and positively with carbon, NO3− and pH, with urease correlated more strongly than β-glucosidase. Only urease correlated with root density. Organic orchard floor management practices may be more effective than CON practices in promoting microbial enzyme activities in the 0–30 cm soil depth intervals of Western Cape apple orchard soils.
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- Date Issued: 2015
Relationship between soil alteration index three (AI3), soil organic matter and tree performance in a 'Cripps Pink/'M7 apple orchard
- Authors: Meyer, André H , Wooldridge, John , Dames, Joanna F
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444038 , vital:74180 , https://hdl.handle.net/10520/EJC157392
- Description: Alteration index three (AI3), which calculates the balances between three microbially-secreted enzymes, potentially enables differences between soils due to contrasting management practices to be quantified in relative terms. The ability of AI3 to distinguish between apple orchard soils under conventional and organic production protocols, and to reflect tree performance, were tested in a maturing 'Cripps Pink'/M7 apple orchard. Activities of β-glucosidase, phosphatase and urease were determined colourimetrically in extracts of tree-row top-soils (0-15 cm) taken during September and January over five consecutive seasons. Soil organic matter content was determined by dichromate oxidation. Stem circumference and yield were measured manually. AI3 correlated significantly (p = 0.05) with soil organic matter, yield and yield efficiency. AI3 may thus be a useful indicator of relative apple tree performance under organic and conventional soil surface management practices.
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- Date Issued: 2014