*4.2.2 Enzymatic activities*

*Tannins - Structural Properties, Biological Properties and Current Knowledge*

a.Supply polyphenol (form 1/form 2) or CuSO4 (100 c.c.) on soil next to the

b.Spraying polyphenol or CuSO4 solution on aerial part of the plant. Let it be

c.Bacterial inoculation: remove leaves from each plant, petiole included (100% wounds done) along the stem, exposing the wound produced. Inoculate helping with a micropipette 10 μl of bacterial solution on the wound directly. Protect the wound with a film at least during 24 h, and then remove it.

d.Watering polyphenol treatments (100 c.c.) 7 and 15 days later from the bacterial inoculation with the corresponding liquid polyphenol (form 1 or form 2).

One of the most interesting parameters for soil quality is the organic carbon content, indicative of the organic matter content of the soil. The organic C induces fundamentally the productivity and fertility of the soil. Its presence in the soil is of great interest from two points of view: environmental (fixation of C in the soil) and

In our experiment (**Table 1**), no significant differences were observed for organic C between the control soil and the soils treated with polyphenols. We know that polyphenols are organic products, and they should be implied in mineralization and humification processes; they could alter soil organic C. However, the addition of polyphenols to the soil did not alter organic C content in the soils studied. This confirms that the doses used for polyphenols in this study are not high enough to

Nitrogen enhances plant growth, improves the quality of crops, and increases seed and fruit production. Nitrogen in the soil is usually supplied by decomposition of organic material, commercial fertilizers, and nitrogen-fixing bacteria. The desirable amount varies between crops; however, too much nitrogen can have adverse

The differences found in soil total N in our experiment (**Table 1**) can be attributable to the variability of soil and our technical analyses; for this reason, it can be

Control− 0.210 a 8.153 a 3.516 a Control+ 0.606 b 9.716 ab 5.153 a CuSO4− 0.526 b 10.363 b 5.116 a CuSO4+ 0.533 b 10.313 b 4.113 a Form 1 0.533 b 11.066 b 4.546 a Form 2 0.556 b 10.600 b 5.673 a *The same letter for each parameter indicates no significant differences between treatment (Tuckey's method, p < 0.05).*

*Total N, total C, and total organic carbon, measured in kiwi soils at the end of the experiment.*

**N total (g/100 g) C total (g/100 g) Corg (g/100 g)**

Application methods for polyphenols and pathogen:

roots. Let it be absorbed during a week.

absorbed (24 h).

Results were the following.

agronomical (soil fertility).

affect this type of parameter.

effects especially on the environment.

*4.2.1 Total organic carbon and total N*

**88**

**Table 1.**

Enzyme activities related to the cycle of elements (carbon, nitrogen, phosphorus, or sulfur) are of paramount importance in soil quality. Among these enzymes we propose the study of phosphatases, ureases, proteases, and different enzymes related to C cycle such as β-glucosidases. Indicators of the microbial population activity (dehydrogenase activity) will give an accurate notion of the impact of the addition of these products on microbial activity. For a general assessment of the functional and structural changes in microbial community, we have carried out several measurements based on soil enzymes.

Most enzymes found in the soil, in particular the hydrolases, are extracellular and have a great environmental interest. In addition, these extracellular enzymes may be free and exposed to rapid denaturation or immobilized together with mineral or organic colloids. Generally, those immobilized enzymes in mineral and/or organic colloid change in their status, nature, and properties (such as kinetics, stability and mobility of enzymes) and are less prone to proteolytic denaturalization, since they are physically and chemically associated with other surrounding chemical compounds.
