High rates of agricultural gypsum affect the arbuscular mycorrhiza fungal community and coffee yield

Abstract

High rates of agricultural gypsum, above the recommended levels, have been used on a regular basis to deepen plant roots and to alleviate recurrent water stress in Cerrado areas. However, very little is known about the consequences of this practice to arbuscular mycorrhizal fungi (AMF). Therefore, the objective of this study was to evaluate whether or not applying high rates of agricultural gypsum affects the mycorrhizal fungi community, glomalin content and coffee yield. The study rates were: 0; 3.5; 7.0; 14 and 56 t•ha-1 of agricultural gypsum applied in the planting row of the coffee plantation on top of the previous recommended gypsum application. Samples were collected for analysis at the depths of 0-20, 20-40 and 40-60 cm at the end of dry and rainy seasons of the year. In the coffee plantation, 16 AMF species were identified. Gigaspora sp. and Glomus macrocarpum were dominant in all situations. The rate of 7 t•ha-1 favored greater diversity of AMF species and the rate of 56 t•ha-1 reduced AMF diversity and mycorrhizal colonization in deeper layers. In the rainy season, there was a linear decrease of easily extractable glomalin-related soil protein (EE-GRSP) levels as the agricultural gypsum rate was increased. Coffee yield was reduced with the highest gypsum rate (56 t•ha-1), even though the coffee plantation had higher phosphorus contents in beans and leaves. This may have resulted from a number of reasons, including a negative effect on the AMF community.

Rhizoglomus variabile and Nanoglomus plukenetiae, Native to Peru, Promote Coffee Growth in Western Amazonia

“…In the four coffee-growing provinces of Peruvian San Martin State, 35 different morphospecies were detected in 12 coffee plantations, with 14-24 morphospecies recovered per province. The majority of previous studies with coffee report a similar AMF species richness (16-37 species) as found in our study [90][91][92][93][94][95][96], with some reporting higher species richness (43 and 79 species; [52,97]). The large variation in AMF species richness was often explained by the coffee production systems, with a generally higher AMF richness under the shadow (shade-green systems), as these systems allow the interaction of coffee with other plant species of the plantations through the belowground AMF network, as well as by different climatic conditions of the regions and the edaphic soil characteristics [93].…”

“…These genera are often the most prevalent in coffee plantations [91,94,98,99]. The genera Rhizoglomus, Sclerocystis, Entrophospora, Dominikia, Ambispora, Diversispora, Gigaspora and Sieverdingia have also been reported from coffee plantations worldwide [90,91,[93][94][95][96][97] but represent a lower species richness, as reflected in the current study.…”

Residual effects of agricultural gypsum on soil chemical and microbiological characteristics

“…Another study reported that applying AG at 7 Mg·ha −1 to soil used for coffee crops resulted in a greater diversity of mycorrhiza species. However, at a high rate of 56 t·ha −1 of AG, this diversity and mycorrhizal colonization of coffee roots was reduced (Cogo et al, 2020).…”

“…In the surface layer of soil, negative correlations between MBC and arylsulphatase activity and between MBN and β‐glucosidase were observed. In soil under coffee crop, there was a linear decrease in extractable glomalin‐related soil protein to mycorrhizal fungi when increased the AG rate (Cogo et al, 2020). There is no doubt the value of AG used as an ameliorant in acid soils decreases aluminium saturation and increases S at deeper layers.…”

“…For instance, the addition of phosphogypsum to the soil with pH 8.1 enhanced enzyme activities and microbial respiration and thus increased the nutrient availability for maize growth and yield (Mahmoud et al, 2021). In tropical acidic soil conditions, few studies have reported the effects of the addition of GA on diversity of bacteria and archaea in the maize and ruzigrass rhizospheres (Bossolani et al, 2020) and on diversity of arbuscular mycorrhizal fungi associated with coffee (Cogo et al, 2020).…”