Why did Cassie feel like crying?

In chapter 8, Cassie feels like crying because the loss of the cotton crop would mean a great loss of income for the Turner family. Mr. Peck's directive means that all of the Turners' hard work would be for naught. Cassie also feels helpless at the turn of events; there is nothing she can do to change what is happening before her eyes, despite the unfairness of it all.
In chapter 8 and the beginning of Chapter 9, we learn that both white and black sharecroppers are required to plow their cotton fields. Ominously, only plantation fields are being plowed. Mr. Peck's reason for requiring Mr. Turner to destroy his cotton crops seems arbitrary at best. He maintains that the AAA committees had somehow made a mistake in calculating how much cotton could be produced. Mr. Peck claims that Mr. Farnsworth allowed too much cotton to be planted.
Moe, Mr. Turner's son, strongly objects to the unfair command to plow up their cotton crops. The crops represent the hard work the entire family has put in, and it is their main source of income. Later in the story, we discover that Mr. Peck's directive was a self-serving one. Plantation owners like Mr. Montier were secretly planting more cotton than they were supposed to. Because they received government money for their cotton crops, the plantation owners decided to increase their financial gain by planting more than the required amount.
The extra cotton crops enriched plantation owners at the expense of the sharecroppers. When Washington threatened to send representatives from the AAA committee to check on the plantations, owners like Mr. Montier forced their sharecroppers to destroy their crops. There was never any directive from Washington to plow up the fields.