Terumot & Ma’aserot

 I first learned about separating terumot and ma'aserot in yeshiva in 2015. In either 2015 or 2016 I designated a half shekel coin to redeem the kedushah onto. At that point in time, I didn't know about bi'ur ma'aser needing to be done at specific times every 4th and 7th year.

I've had the same coin for 9 or 10 years and have periodically used it to redeem produce. I did not do bi'ur ma'aser on it yet but will destroy it before Pesach of this year.

How do I know when the coin is “full” and I need to replace it?

How many times can I redeem produce onto it?

If I “fill up” one coin before the designated time to do bi'ur ma'aser, should I destroy the coin and start a new one or do I have to keep the “full” coin until the 4th or 7th year and only them destroy it?

If I keep the full coin until the year in which I need to destroy it, is there some special procedure when I start the new coin?

Do I need to transfer the kedushah from the full coin to the new coin? Thanks

Fully ripe lemons that are growing on my tree now in Israel - are they ma'aser ani or ma'aser sheni? Presumably they grew more than a 1/3 prior to this most recent Tu Bishevat. Same question about my kumquats - they are smaller and unclear when they grew, but certainly most likely more than 1/3 prior to Tu Bishevat. 

Question

Hello Rabbi, Happy Chanukah!I would appreciate guidance on a somewhat complex halachic question.

I harvested 100 kg of olives for oil production:

• 80 kg of them were hefker (ownerless),
• 20 kg belonged to someone who gave me permission to harvest them.

When I arrived at the olive press, I was told this was too small a quantity to process alone, so I waited for someone to join me. Another person arrived with 50 kg of olives, and oil was produced from a total of 150 kg. We then divided the oil according to the percentage each of us contributed.

A. Of the oil that I received, from how many kilograms must I separate terumot and ma'aserot — from 150, 100, or 20?

B. Do I need to coordinate with the other person whose oil was mixed with mine? I understand there may be an issue of bilah belach, that liquids mix.

Is it permissible to place terumah produce in a compost bin for the purpose of making compost, and once it has decomposed, may it be used to fertilize the soil?

I see on my mandarin tree that some of the flowers set right before 15 Shevat. Assuming that citrus fruits also follow chanatah, how would I deal with terumot and ma'aserot? Would I need to take from each fruit separately?

I signed up as a member of Beit Ha'otzar at one point last year. Now that Rosh Hashanah has just passed, do I need to renew my membership, as it's a new ma'aser year?

There is a guava tree in my apartment building’s shared courtyard (with 15 families). Every week I pick two to four fruits and take them home. Am I supposed to take terumot and ma’aserot from the guava with a blessing? If the tree was in a public playground, would its fruit also be subject to terumot and ma’aserot?

I didn’t quite understand the issue of the coin used for terumot and ma‘aserot. What exactly is this coin? Is it just regular money? Also, does this mean I can’t eat fruit from a garden if I don’t have the coin with me at that moment—for example, if I’m at the school where I work and there are fruit trees there?

Are the fruit trees in public parks hefker and does it matter how much you take and what you plan on doing with it? For instance, large-scale olive harvest.