This study evaluates the transcriptome of 3 Arabidopsis thaliana genotypes (Col-0, phf1 and phr1/phl1) growing in soil treated under a gradient of fertilization regimes. Overall design: Each of the three Arabidopsis genotypes was grown in soil from all 18 plots (6 plots per P treatment). In addition, a 4th P regimen designated 'Low+P' was created by adding additional P to a set of pots with low P. The amount of P added to these pots is based on the difference in total P between Low and High P plots. The average difference between Low and High P over all the plots is 42 mg P per kg soil . Per pot, this is 12.6 mg P (accounting for 300 g soil per pot). Thus, a 10 ml solution consisting of 4.2 mg P in the form of 20% K2HPO4 and 80% KH2PO4 was added to the pots in 3 applications (Week 2, 4 and 6) before watering (in order to distribute the P through the soil).