Estimating the yield of crops

Objective

Calculate how much yield will be produced by an agricultural field where potatoes are planted.

Materials

•	This worksheet
Procedure

1)	Look at the Near Infrared and Red images below. 

Near infrared band	Red band

For the points A, B and C, the pixel values for the reflectance in the near infrared and red region of the spectrum are given in the table below:

Point	Near Infrared	Red	NDVI	
A	204	85		
B	185	57		
C	254	71		

Calculate the Normalised Difference Vegetation Index (NDVI) by using the values in the red and NIR image.

2)	Assume that all three fields are planted with potato plants. In the three previous years satellite images were collected from the same region, at the same month as the images above. The NDVI values of those years and the final yield in tons per hectare for the particular fields are given in the following table:

Year	Yield	NDVI	
1	15	0.45	
2	12	0.38	
3	18	0.52	

If we assume that the relationship between NDVI and yield is linear, estimate the yield for this year, based on the NDVI calculated previously.