Farmers use artificial fertilisers to maintain or increase yield from grain-producing crop plants such as wheat.
Artificial fertiliser is used to replace mineral ions removed from the land when crops are harvested. One of these mineral ions is phosphate.
Give two examples of biological molecules containing phosphorus that would be removed when a crop is harvested.
Scientists investigated changes in the use of phosphate fertiliser in a grain-producing region between 1980 and 2015. They also investigated changes in the fertiliser response ratio. This ratio shows how many kg of grain are produced for each kg of fertiliser used.
The table below shows the results of their investigation:
| Year | Phosphate fertiliser used (kg ha−1 yr−1\text{kg ha}^{-1}\text{ yr}^{-1}kg ha−1 yr−1) | Fertiliser response ratio (kg grain / kg fertiliser\text{kg grain / kg fertiliser}kg grain / kg fertiliser) |
|---|---|---|
| 1980 | 20 | 15.0 |
| 1985 | 30 | 12.0 |
| 1990 | 45 | 9.5 |
| 1995 | 55 | 7.8 |
| 2000 | 65 | 6.4 |
| 2005 | 72 | 5.5 |
| 2010 | 80 | 4.8 |
| 2015 | 85 | 4.5 |
Use these data to calculate the difference in the mass of grain produced per hectare in 1980 compared with 2015. Show your working.
Use the data in the table to evaluate the use of phosphate fertilisers on grain-producing crops in this region.
