Page 09 16. The table below shows the biological and economic yields of four different crops. Crop Biological yield (tonnes of dry mass/hectare) Economic yield (tonnes of dry mass/hectare) pea 10 2 rice 15 10 wheat 30 8 potato 30 10 The crop with the highest harvest index is A pea B rice C wheat D potato. 17. The graph below shows the levels of nitrogen and phosphorus applied to crops in an area of Scotland between 1986 and 2006. 130 120 110 100 90 50 45 40 35 30 1986 1990 1994 1998 2002 2006 Nitrogen applied (kg/ha) Phosphorus applied (kg/ha) In which year was there the smallest difference between the levels of nitrogen and phosphorus applied? A 1998 B 2000 C 2002 D 2006 [Turn over