Trouble with 'for' loop: Length of values (0) does not match length of index (52)

Question

I am newer to python, and am trying to write a 'for' loop to perform a calculation on one column in a dataframe and put the results in another column. However, I'm getting the following error:

ValueError: Length of values (0) does not match length of index (52)

What is the problem in my code?

#Import modules
import pandas as pd
import numpy as np
import os

#Read dataframe
df = pd.read_csv(file)
df.head(52)

Here is the data:

    Sample_ID   longitude   latitude    n_ppm   Mehlich_3_ppm   k_ppm   pH  Buffer_pH   OM  Zn_ppm
0   1   -100.922987 39.248554   32  20  29  7.1 7.2 2.7 3.4
1   2   -100.921920 39.248792   35  13  22  7.2 7.3 2.7 3.0
2   3   -100.920808 39.248584   34  8   21  7.5 7.3 2.6 1.2
3   4   -100.919779 39.248591   32  8   33  7.4 7.3 2.6 1.2
4   5   -100.918698 39.247933   42  7   26  7.1 7.1 2.6 1.2
5   6   -100.919457 39.247719   42  7   28  7.4 7.3 2.7 1.5
6   7   -100.920822 39.247916   36  9   32  7.4 7.3 2.8 1.6
7   8   -100.922241 39.247906   36  35  25  7.4 7.3 2.6 3.4
8   9   -100.923254 39.247781   31  35  26  7.5 7.3 3.0 4.2
9   10  -100.924217 39.247858   41  67  40  7.2 7.3 3.0 4.7
10  11  -100.925033 39.246966   50  46  26  7.6 7.3 2.9 2.3
11  12  -100.924190 39.246857   55  71  34  6.9 7.1 3.0 4.3
12  13  -100.923128 39.247089   50  68  27  7.2 7.2 2.7 3.6
13  14  -100.921795 39.246824   50  63  20  7.2 7.2 2.9 3.9
14  15  -100.920870 39.247048   50  43  32  7.2 7.2 3.1 3.1
15  16  -100.919414 39.246841   50  14  32  7.2 7.2 2.7 1.5
16  17  -100.918580 39.247120   50  10  23  7.3 7.3 2.6 1.2
17  18  -100.917600 39.246849   50  9   20  7.3 7.3 2.4 1.1
18  19  -100.917600 39.246111   50  23  36  7.3 7.3 3.3 1.4
19  20  -100.918410 39.245921   50  28  26  7.3 7.3 3.2 1.1
20  21  -100.919478 39.246194   50  99  23  7.1 7.1 3.4 3.0
21  22  -100.920773 39.245991   38  27  38  7.3 7.3 3.3 2.6
22  23  -100.921784 39.246063   37  26  40  7.4 7.3 3.4 3.5
23  24  -100.923103 39.246296   30  48  36  7.3 7.3 3.4 3.2
24  25  -100.924202 39.246112   34  64  33  7.1 7.2 3.2 3.1
25  26  -100.925255 39.246100   41  30  36  7.1 7.2 2.9 2.6
26  27  -100.925431 39.245284   33  29  34  7.7 7.4 3.0 2.3
27  28  -100.924429 39.245093   43  52  23  6.8 7.1 3.7 3.2
28  29  -100.923143 39.245226   36  24  36  7.1 7.2 2.9 3.8
29  30  -100.922008 39.245047   38  36  36  7.0 7.1 3.2 3.6
30  31  -100.920764 39.245258   39  17  35  7.2 7.2 3.3 3.5
31  32  -100.919717 39.244983   41  10  26  7.2 7.2 3.1 1.8
32  33  -100.918345 39.245352   37  13  27  7.2 7.3 3.3 1.7
33  34  -100.917390 39.245077   34  14  21  7.1 7.2 2.9 1.3
34  35  -100.917553 39.244407   41  67  22  7.1 7.2 3.6 1.9
35  36  -100.918440 39.244260   41  12  34  7.2 7.2 2.9 1.3
36  37  -100.919476 39.244483   32  9   23  7.4 7.3 2.8 1.2
37  38  -100.920955 39.244112   45  25  39  7.1 7.2 3.0 4.5
38  39  -100.921705 39.244254   36  27  39  7.2 7.2 3.2 3.8
39  40  -100.923370 39.244238   33  28  35  7.0 7.2 2.7 3.1
40  41  -100.924262 39.244383   45  32  32  7.1 7.2 3.0 3.0
41  42  -100.925087 39.244483   40  12  29  7.2 7.2 2.9 2.7
42  43  -100.924365 39.243440   30  59  23  6.9 7.1 3.8 3.2
43  44  -100.923045 39.243196   43  10  22  7.2 7.3 2.6 2.9
44  45  -100.921845 39.243471   37  23  20  7.1 7.2 3.1 3.3
45  46  -100.920755 39.243252   35  21  37  7.2 7.2 3.2 5.1
46  47  -100.919772 39.243325   45  12  36  7.1 7.2 2.6 2.1
47  48  -100.918568 39.243501   40  9   20  7.0 7.2 2.7 1.0
48  49  -100.919691 39.242702   34  8   32  7.2 7.2 3.0 2.2
49  50  -100.920656 39.242624   35  15  20  7.4 7.3 3.2 4.8
50  51  -100.922180 39.242513   36  9   28  7.0 7.2 2.8 2.4
51  52  -100.922826 39.242723   34  10  37  7.1 7.2 4.3 2.8

organicMatterField = df['OM']
yieldGoal = 150
nitrogenField = df['n_ppm']
pca = 0


nitrogen_needed = []
for nit in df['n_ppm']:
    nit = ((1.6 * int(yieldGoal)) - (organicMatterField * 20) - (nitrogenField) - float(pca))

#Create a new column within the dataframe        
df['Nitrogen recommendation (ppm)'] = nitrogen_needed

print(df)

The error is thrown here. It may be because my 'for' loop isn't written right, but I'm not sure.