sample          treatment       N_pcent  N15   C_pcent  C13  
diet_red_58     grac            9.5      13.5  48.9     -18.4  
diet_red_83     grac            12.7     12.2  43.0     -16.9  
diet_red_14     grac            10.6     12.3  42.2     -17.6  
diet_red_3      grac            10.9     13.2  41.7     -17.2  
diet_red_119    grac            10.3     13.7  43.0     -16.5  
diet_white_67   pods            10.9     14.1  42.6     -15.6  
diet_white_18   pods            11.3     12.4  41.4     -14.5  
diet_white_66   pods            10.8     13.3  44.8     -14.1  
diet_white_59   pods            12.0     13.1  44.4     -14.4  
diet_white_49   pods            10.9     13.9  43.1     -14.1  
diet_blue_105   grac_and_pods   9.9      13.7  41.4     -14.9  
diet_blue_36    grac_and_pods   12.3     11.6  41.2     -15.6  
diet_blue_88    grac_and_pods   9.3      13.1  39.2     -14.5  
diet_blue_12    grac_and_pods   9.9      12.3  40.8     -14.9  
diet_blue_5     grac_and_pods   10.0     13.2  40.4     -15.3  
diet_black_60   mud             10.6     13.6  41.0     -17.1  
diet_black_102  mud             10.5     14.3  40.0     -17.1  
diet_black_4    mud             10.4     15.8  39.8     -18.4  
diet_black_79   mud             11.1     14.1  39.9     -16.8  
diet_black_71   mud             10.8     14.9  39.9     -17.1  
pods_april_1    pods_field      8.1      9.7   33.4     -13.3  
pods_april_2    pods_field      7.1      9.2   31.8     -14.0  
pods_april_3    pods_field      7.7      9.1   34.0     -12.6  
grac_april_1    grac_field      2.8      10.7  33.3     -16.2  
grac_april_2    grac_field      3.5      9.9   36.5     -15.3  
grac_april_3    grac_field      3.5      10.1  33.0     -17.2