Crecchio, C

DICHIO, Bartolomeo

MININNI, ALBA NICOLETTA

PASCAZIO, SILVIA

Scagliola, M

SOFO, Adriano

XILOYANNIS, Cristos

English

Archivio della Ricerca - Università della Basilicata

1Abstracts441NITROGEN DYNAMICS AND N-CYCLING BACTERIAL COMMUNITIES IN A MEDITERRANEAN OLIVE ORCHARD UNDER A SUSTAINABLE FARMING SYSTEM1 1 1, Alba N. Mininni1, a l  i i 2, i  il anni 2, A ian  3 1Department of Soil, Plant and Food Sciences (DiSSPA), Università degli Studi di Bari “Aldo Moro”, Via Amendola, 165, 70126 Bari, Italy, 2Department of European and Mediterranean Cultures: Architecture, En-vironment and Cultural Heritage (DiCEM), Università degli Studi della Basilicata, Via San Rocco, 3, 75100 Matera, Italy, 33 School of Agricultural, Forestry, Food and Environmental Sciences (SAFE), Università de-gli Studi della Basilicata, Viale dell’Ateneo Lucano, 10, 85100 Potenza, ItalyObjectivesIn the recent years, soils has been recognized to play a double role in the entire agro-ecosystem: it is import-ant for a good production as well as for a healthy environment [1, 2]. The conventional, non-sustainable, agronomic practices should evolve in a more sustainable management addressed to ameliorate the ecological networks and nutrient cycling in which soil microorganisms are involved [3, 4, 5].The main objective of this study was to analyze N dynamics in an olive orchard managed with sustainable agricultural practices. For improving the system and better characterizing the components responsible for the transformation of the different forms of soil N and their availability for plants, a biological and biochemical soil N indicator was used, and the expression of genes of N-cycling bacterial communities were investigated.MethodThe trial was in a 2-ha mature olive grove located in outhern Italy managed using sustainable and organic agricultural practices for 15 years. lants were drip irrigated with urban wastewater total N  1 .3 mg -1  with a mean presence of Escherichia coli, nterococci and Clostridium spores of 35 ,  and 23  F  1  m -1, respectively) and lightly pruned every year The soil was permanently covered by spontaneous self-seeding weeds mowed twice a year. over crop residues and prunings were shredded and left on the ground as mulch. Two sampling areas were identi ed: along the row under the emitters) and along the in-ter-row (rain-fed). Three soil samplings (composite bulk samples collected from the 0-10 cm soil layer) were performed in a year.  The degree of soil uality was expressed by the ratio Nc Nk, where Nk is jeldahl total soil N, while Nc is a linear function of microbial biomass carbon and N mineralization capacity, combined with three enzyme activities, calculated by the following e uation [5]:Total N  (0.3 10-3) microbial biomass   (1.4 10-3) mineralized N  (13. 10-3) phosphomonoesterase + ( . 10-3) -glucosidase + (1. 10-3) ureaseThe expression levels nitrogenase (nifH), ammonia monooxygenase (amoA), nitrite reductase (nirK and nirS), and nitrous oxide reductase (nos ) were determined by real-time uantitative , using speci c primers and microbial reporter genes (from Nitrosomonas europaea, Azospirillum irakense, Azospirillum brasiliense, Pseudomonas stutzeri and Pseudomonas uorescens). Total soil NA extraction was carried out by NA ower oilTM Total NA Isolation it ample (Mobio) followed by a Nase treatment. etrotra-cripts were puri ed by using the izard  el and  lean- p ystem ( romega).Microbial biomass  was determined by the fumigation-extraction method [ ]. Mineralized N was evaluated as the difference of inorganic N at the beginning and at the end of an incubation period [5]. Inorganic N was determined by the method of remner [ ]. rease, phosphomonoesterase, and -glucosidase activities were measured following the methods described in [7], [8] and [9], respectively. Together with N analyses, counts of speci c N-cycling bacterial groups, soil organic matter, soil moisture and soil physical structure, were monitored.442ResultsIn a soil, a large number of physical, chemical and biochemical properties are involved. However, due to the impossibility of considering all of them, it is of key importance to make a selection. In this study, the ratio Nc Nk exhibited all the attributes of a good soil fertility indicator, as it was sensitive to changes that occur in the soil, capable of re ecting the improvement of soil uality and not too sensitive to environmental and uctuations. Nc Nk showed signi cant differences in the different areas of each orchard (row and inter-row), being generally higher along the row (in the areas wetted by drippers and with high organic matter content) and so indicating a better soil uality. This ratio, together to the microbial biomass carbon, N mineralization capacity and enzyme activities, gave a precise idea on nitrogen soil dynamics ( xation, mineralization, im-mobilization, organication, nitri cation and denitri cation) in the different parts of the olive orchard studied. In the areas along the row, a higher bacterial functional activity and diversity was also found, compared to the inter-row areas.The se uences of NA with high phylogenetic information content, such as the r NA genes, has been used for the description of the N microbial networks, increasing our knowledge on the bacterial diversity in soils [10]. tudies based on NA mainly provide information on the community structure, while the NA studies, and in particular the analysis of m NA expression, provide information on the activities of speci c populations. onsidering the different conditions in the different parts of the orchard (along the row, under the emitters, with high soil moisture  and along the inter-row, where cover crop residues and prunings were shredded) and the seasonal effects (mainly due to rainfall distribution, soil moisture and soil temperature), m NAs from N-cycling communities were considered for this study. The number of ammonifying bacteria, proteolytic bacteria and nitrogen- xing Azotobacter in the wetted areas under the drippers were signi cantly higher than along inter-rows, whereas denitrifying Pseusomonas were not signi cantly different between the two parts of the orchard. The higher bacterial counts along the row were accompanied by higher expressions of nifH, amoA, nirK and nirS.ConclusionsThis study con rms the need for Mediterranean orchards to encourage farmers to practice soil management based on organic matter inputs associated with zero tillage, in order to improve soil fertility. The increase of knowledge on biochemical processes of the soil microorganism involved in soil N dynamics in uencing N availability for plants, can lead to optimize management strategies for a modern and multifunctional concept of agriculture, based on product uality, environmental protection, resource saving and promotion of human health.References[1] ofo, A., alese, A.M., asacchia, T., ichio, ., iloyannis, . 2012. In: Ahmad, ., rasad, M.N. . (eds) Abiotic tress esponses in lants. pringer, New ork, A. p. 105-129 [2] ing, . ., iceno, .M., Heuer, H., einert, N., ohrmann, A. ., arrillo, A., Andersen, . ., astel-lanos, T., Tebbe, . ., malla, . 2013. o  N  8: e59497 [3] raf, . .H., ones, .M., Hallin, . 2014 o  N  9: e114118 [4] il- otres, F., Trasar- epeda, ., eir s, M. ., eoane, . 2005. oil iology  iochemistry 37: 877-887 [5] Trasar- epeda, ., eir s, M. ., il- otres, F., eoane, . 1998. iology and Fertility of oils 2 : 100-106 [6] ance, . ., rookes, . ., enkinson, . . 1987. oil iology  iochemistry 19: 703-707  [7] remner, .M., 1995. In: lack, .A. et al. (eds) Methods of oil Analysis. A A, A, A, Madi-son, I, A. p. 1179-1237 [8] Tabatabai, M.A., remner, .M., 1972. oil iology  iochemistry 4: 479-487 [9] ivazi, F., Tabatabai, M.A., 1977. oil iology  iochemistry 9: 167-172 [10] ivazi, F., Tabatabai, M.A. 1988. oil iology  iochemistry 20: 601-606

Nitrogen dynamics and N-cycling bacterial communities in a Mediterranean olive orchard under a sustainable farming system

https://iris.unibas.it/bitstream/11563/120762/1/2016%20-%2019th%20Nitrogen.pdf

Nitrogen dynamics and N-cycling bacterial communities in a Mediterranean olive orchard under a sustainable farming system

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