Water distribution in flysch soil and status of olive trees (Olea europaea L.) under interval and continuous drip irrigation

Namen magistrske naloge je bil raziskati vpliv potencialne strategije za varčevanje z vodo s pomočjo intervalnega kapljičnega namakanja ob vzdrževanju vsebnosti vode v tleh bližje kritični točki (KT) kot poljski kapaciteti (PK), t. j. deficitnega upravljanja količine talne vode (DUKTV). V oljčniku na Serminu s tlemi na flišni podlagi, meljasto glinaste teksture (PK 40 vol. %, KT 30 vol. %) sta bili 2021 vzpostavljeni dve strategiji namakanja: intervalno (I) in neprekinjeno (N) podzemno kapljično namakanje ter nenamakano, kontrola (K). Pri I smo namakali v treh ali štirih intervalih z enournimi odmori. Proučevali smo vpliv DUKTV na razporejanje vode v talnem profilu, na vodni potencial rastlin (VP) (datumi vzorčenja za oboje so bili 29. 6., 16. 8. in 15. 9.) in na spremembo obsega debla (OD), kjer so bile ves čas polurne meritve. Vsebnost vode v tleh (VV) smo gravimetrično izmerili na 15, 35 in 55 cm globine v oddaljenosti 10, 20 in 30 cm v obeh smereh od namakalne cevi, pri kapljaču in med dvema kapljačema, ki so bili 60 cm narazen. Povprečni VV pri K po datumih je (v vol. %) 18,0 ± 0,5, 16,7 ± 0,3 in 13,7 ± 0,2, pri I 23,2 ± 0,7, 20,0 ± 0,3 in 18,3 ± 0,5 ter pri N 23,3 ± 0,7, 20,0 ± 0,3 in 17,9 ± 0,3. Povprečni VV se pri K po globini ne spreminja in ima pričakovano statistično značilna najmanjša povprečja. Med I in N ni statistično značilnih razlik v VV (p=0,93) na vseh obravnavanih globinah. Prav tako ni statistično značilnih razlik v VV med in ob kapljaču, kar nakazuje na dobro razporejanje vode v horizontalni smeri. Namakanje je imelo pozitiven vpliv na status rastlin, kar se je odrazilo v višjem VP oljk, ki so bile namakane in v ohranjanju oz. povečanju OD. VP pri K po datumih je bil (v MPa) -1,9 ± 0,1, -2,8 ± 0,1 in -4,9 ± 0,3, pri I -1,8 ± 0,1, -2,3 ± 0,1 in -3,0 ± 0,2 ter pri N -1,8 ± 0,1, -2,2 ± 0,1 in -2,0 ± 0,1. Med I in N ni statistične razlike v VP (p=0,31). N je imelo boljše rezultate na spremembo OD, v povprečju se je OD povečal za 1± 0,5 mm od začetka namakanja, medtem ko se je OD oljk pri I v povprečju zmanjšal za 1 ± 0,6 mm. Ob upoštevanju DUKT I ni imelo vpliva na razporejanje vode v tleh in na oskrbo oljk z vodo v primerjavi z N.The purpose of the master\u27s thesis was to examine a potential strategies for conservation of water by implementing pulse drip irrigation while maintaining the soil water content closer to the critical point (CP) than the field capacity (FC), i.e. deficit management of soil water content (DMSWC). The experiment was conducted in an olive orchard on flysch substrate where two irrigation strategies were established: pulsed (I) and continuous (N) subsurface drip irrigation as well as a control (K) strategy, where there was no irrigation. I was implemented as a set of three or four irrigation periods, with one hour pauses per each active irrigation period. The scope of our research with the DMSWC included the impact on water distribution in the soil profile, water potential of olive trees (WP) (sampling dates for both were on 29/6, 16/8 and 15/9) and finally, changes in trunk circumference (TC) where there were half-hourly measurements. The volumetric water content in the soil (VWC) was measured at the depths of 15, 35 in 55 cm at a distance of 10, 20 and 30 cm in both directions from the irrigation pipe, at the dripper and between two drippers that were 60 cm apart. The average VWC for K by dates is (in vol. %) 18.0 ± 0.5, 16.7 ± 0.3 and 13.7 ± 0.2, for I 23.2 ± 0.7, 20.0 ± 0.3 and 18.3 ± 0.5 and for N 23.3 ± 0.7, 20.0 ± 0.3 and 17.9 ± 0.3. Average VWC for K showed statistically significant lowest averages. A comparison in results between I and N shows no statistically significant difference in VWC (p = 0.93) at all depths considered. There was also no statistically significant difference in the water content of the soil between and near the dripper, which indicates good water distribution in the horizontal direction. Irrigation had a positive impact on the status of the plants, resulting in a higher WP of the irrigated olive trees as well as in the preservation and increase of TC. WP at K by dates was (in MPa) -1.9 ± 0.1, -2.8 ± 0.1 and -4.9 ± 0.3, at I -1.8 ± 0.1, - 2.3 ± 0.1 and -3.0 ± 0.2 and for N -1.8 ± 0.1, -2.2 ± 0.1 and -2.0 ± 0, 1. There is no statistical difference in WP between I and N (p=0.31). N had better impact on TC. TC measurements show an average increase of 1 ± 0.5 mm from the beginning of irrigation in N, while in the case of I shrinkage of 1 ± 0.6 mm. I, by considering DMSWC had no effect on the soil water distribution or water supply of olives compared to N