Forecrop Effects on Abundance and Diversity of Soil Microorganisms during the Growth of the Subsequent Crop

Abstract

Plant residues introduced into the soil influence the soil’s physical, chemical, and consequently, biological parameters, which have an influence on plant health and yields. This study was undertaken to evaluate the effects of the cultivation of widespread plant species, faba bean (Vicia faba L., F) and wheat (Triticum aestivum L., W) (as forecrops) grown under conventionally tilled fields, on the diversity of microorganisms and the enzymatic activities of soil during the growth of the subsequent wheat. Bulk soil samples (0–20 cm) were taken three times from two months after residue incorporation into the soil to the maturity of the subsequent wheat crop in order to assess the fungal and bacterial communities (Next Generation Sequencing (NGS), terminal restriction fragments lengths polymorphism (t-RFLP)), ammonia oxidizing archaea (t-RFLP, denaturing gradient gel glectrophoresis (DGGE)), and the enzymatic activity of soil. Differences in the genetic structure of ammonia-oxidizing archaea (AOA) were observed for each treatment and sampling term, indicating that plant and weather conditions are the driving force for microorganism selection and adaptation. We observed that the fungal community was more influenced by the forecrop type used than the bacterial community. The activities of the enzymes changed in response to the forecrop and sampling period. A higher number of microorganisms that are associated with plant benefits with respect to nutrients and growth, as well as higher amounts of N in the residues, was noted in faba bean than in wheat soil. This could indicate better growth conditions after faba bean and, consequently, better yield quality and quantity. This may also indicate some protective role of the soil after faba bean against pathogens, which may be connected with lower fungicide requirements. The obtained results lead to a deeper understanding of the microorganism reactions to faba bean and wheat residues during wheat cultivation. In addition, they may be helpful in improving our understanding of subsequent crop yield responses to forecrops.

The Effect of Alfalfa Mineral Fertilization and Times of Soil Sampling on Enzymatic Activity

“…It should be added that in the present studies, basic soil parameters were at a low level (pH, organic matter content). High dehydrogenases activity recorded in the present experiment was confirmed by other studies [8,22], also in which the time of taking soil samples significantly differentiated the activity of this enzyme. According to Pan et al [38] and Antonkiewicz et al [39], the activity of enzymes increases with the introduction of fertilizers into soil and with the increase of carbon substrates in the soil, which was confirmed in the present experiment.…”

“…Many studies [11,14,36,37] indicate a significant effect of the timing of soil sampling on the level of enzymatic activity. According to Siczek et al [8], the activity of urease in soil with faba bean was higher than the activity of this enzyme in soil with wheat. A similar response was noted for dehydrogenases, which is an intracellular enzyme of microorganisms, connected with C-cycle [8].…”

“…According to Siczek et al [8], the activity of urease in soil with faba bean was higher than the activity of this enzyme in soil with wheat. A similar response was noted for dehydrogenases, which is an intracellular enzyme of microorganisms, connected with C-cycle [8]. Mineral fertilizers applied in the present studies and in the studies of other authors [3,5] significantly increased urease activity in soil.…”

“…Applied in alfalfa cultivation, iron affects soil enzymatic activity and thus the potential viability of plants to grow [5][6][7]. According Siczek et al [8], soil enzymes are similar to enzymes in other living organisms (e.g., in plants). Enzymes catalyze reactions breaking down organic matter, and their presence in soil is an indicator of its biochemical and microbial soil activity [9][10][11].…”

“…Many studies have proved that increasing soil organic matter content by the addition of organic manures can increase the biological activity in soil. Ploughed-in crop residues affect the diversity and abundance of soil fungal and bacterial communities and enzymatic activity [8].…”