Zpráva o činnosti v roce 2006 (10MB) - SVT

Obr. 1 Trvalý travní porost
Fig. 1 Permanent grassland
Obr. 2 Porost kostøavy èervené
Fig. 2 Fescue crop stand
Obr. 3 Volná pùda bez porostu
Fig. 3 Free land without crop stand
Použité umìlé zadeš ovací zaøízení umožòuje nastavit
intenzitu kropení mìøicího stanovištì o ploše 0,5 m 2 vodou,
udržovat tuto intenzitu na konstantní úrovni po celou dobu
mìøení a odtok vody z ohranièené plochy mìøicího stanovištì
odeèítat ve stanoveném èasovém intervalu. Ze známé
intenzity kropení a èasového prùbìhu odtoku vody z mìøicí
plochy se vypoèítá rychlost infiltrované vody do pùdy a
rychlost povrchového odtoku vody.
Výsledky
Pro porovnávací mìøení byl pro všechny varianty zvolen
postøikový tlak 200 kPa, pøi nìm je intenzita postøiku 1,98
l.min -1 .m -2 . To odpovídá rovnomìrné deš ové srážce
118 mm.h -1 . Stanovištì byla vybrána tak, aby se co nejménì
odlišovaly ve svažitosti a v pùdním druhu. Vlhkost pøed
postøikem je u variant s trvalým travním porostem a úhorem
bez porostu na shodné úrovni cca 15 % hm u kostøavy
èervené je o témìø 6 % nižší. Drsnost pùdy byla hodnocena
pouze ve variantì na pùdì bez porostu.
The utilized artificial spraying equipment can adjust the
measuring site spraying intensity on area of 0,5 m 2 with
water, maintain that intensity on constant level during whole
measuring period and read the water runoff from measuring
site defined area in determined time interval. From the known
spraying intensity and water runoff time course from the
measuring area can be calculated the water infiltration speed
into soil and water surface runoff speed.
Results
For the comparative measuring was chosen the spraying
pressure of 200 kPa for all variants with the spraying intensity
1,98 l.min -1 .m -2 . This corresponds with the regular rainfall
of 118 mm.h -1 . The sites were chosen to vary as least as
possible in plot inclination and type of soil. Moisture before
spraying is at approx. identical level of 15 % by weight
for the variants with permanent grassland and fallow without
crop cover. For fescue that moisture is by almost 6 %
lower. The soil roughness was evaluated only in the variant
„soil without crop cover“.
For mutual comparison of water soil permeability (infiltration)
and water surface runoff among the variants we
have transferred the measured values to their instantaneous
unit speed during the recorded time intervals (Fig. 2 -
4). This method will enable to compose also the values of
measuring which have not identical measuring interval.
Besides the runoff and infiltration speed the important indicator
is the flood beginning, i.e. the surface water outflow
to the measuring vessel.
For the permanent grassland with fully connected crop
stand and root system the water permeabitity was 4-time
higher in comparison with the black fallow and almost twice
higher as compared with the fescue monoculture under
identical conditions, where water flows into the gaps
between unconnected hills and its runoff is accelerated.
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