For the source of the harvest, God’s children are called to look to God who with his powerful hand upholds all things, even “...leaf and blade, rain and drought, fruitful and lean years, food and drink...” (Heidelberg Catechism, Lord’s Day 10, Question and Answer 27). As a response for the harvest, God’s people are called to give him thanks.
The fourth petition of the Lord’s Prayer also expresses this dependence on God as provider (Heidelberg Catechism, Lord’s Day 50, Question and Answer 125).