(1) The government says Ethiopia should stop leaning on other nations or risk being seen as Africa's perpetual begging bowl.
(2) ... some fields are now green with plump cabbages, potatoes, garlic and tomatoes as farmers try their hand at cultivating vegetables.
(3) Critics say lack of ownership sows the seeds of insecurity and discourages farmers from investing long-term.
In English usage, there are some fixed rules that we have to follow. (1) shows that when using 'stop' and 'risk', we must use the '-ing' form of a verb (leaning, being) instead of the infinitive form (to lean, to be). That is, we wouldn't say 'The government says Ethiopia should stop to lean on other nations or risk to be seen as Africa's perpetual begging bowl'.
(2) and (3) show a set structure that we must follow: to try one's hand (not 'hands') at (-ing) and to discourage someone from (-ing).
There are many other rules and phrases in the language. Read, question and practise often, and you'll get it right.