This report describes standardized data for “Maize-grain zinc and iron concentrations as influenced by agronomic management and biophysical factors: a meta-analysis”. These data were standardized on 2025-10-01 by Cedric Ngakou with this R script. The original data have a CC-BY license. Here you can download the standardized data.

This is the full citation of the data set:

Job Kihara; Dominic Mwanzia Mutambu; Michael Kinyua; Gudeta W. Sileshi; Kalimuthu Senthilkumar; Siyabusa Mkhulani; Lydiah Nturibi; Mina Devkota; Kazuki Saito; Peter Bolo; Andrew Sila (2025). Maize-grain zinc and iron concentrations as influenced by agronomic management and biophysical factors: a meta-analysis. International Institute of Topical Agriculture. Not versioned. doi:10.25502/w6w2-6p25/d

You can also consult the accompanying paper.

The dataset has 2355 records and 50 variables for maize in 22 countries (Argentina, Bangladesh, Brazil, Chile, China, Egypt, Ghana, India, Iran, Kenya, Libya, Malawi, Malaysia, Nigeria, Pakistan, Poland, Serbia, Spain, Tanzania, United States, Zambia, Zimbabwe). The dataset has 5 treatment(s): Fe_fertilizer, K_fertilizer, N_fertilizer, P_fertilizer, Zn_fertilizer.


These are the first 25 records:

records
reference trial_id planting_date on_farm is_survey treatment crop yield_part yield yield_moisture fertilizer_used N_fertilizer P_fertilizer K_fertilizer Zn_fertilizer Fe_fertilizer OM_used OM_type OM_amount inoculated irrigated land_prep_method rain grain_N grain_Fe grain_Zn grain_protein country location longitude latitude geo_from_source soil_type soil_pH soil_pH_KCl soil_pH_CaCl2 soil_sand soil_clay soil_silt soil_texture soil_SOM soil_SOC soil_N soil_K soil_P soil_P_method soil_Fe soil_Zn
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 6640 NA TRUE 0.0 0.00 0.00 25 NA FALSE none NA TRUE FALSE unknown NA NA 37.90663 5.722892 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 6065 NA TRUE 125.0 37.50 37.50 25 NA FALSE none NA TRUE FALSE unknown NA NA 21.23660 5.754328 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 7844 NA TRUE 187.5 56.25 56.25 25 NA FALSE none NA TRUE FALSE unknown NA NA 25.16573 6.157573 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 8204 NA TRUE 250.0 75.00 75.00 25 NA FALSE none NA TRUE FALSE unknown NA NA 29.49781 6.009264 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 6454 NA TRUE 125.0 37.50 37.50 25 NA FALSE none NA TRUE FALSE unknown NA NA 14.95197 5.686396 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 8221 NA TRUE 187.5 56.25 56.25 25 NA FALSE none NA TRUE FALSE unknown NA NA 18.80550 6.325265 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Kaleeswari 2019 Agricultural Research Station, Bhavanisagar-NA NA NA FALSE maize grain 8554 NA TRUE 250.0 75.00 75.00 25 NA FALSE none NA TRUE FALSE unknown NA NA 23.26397 7.084405 NA India Agricultural Research Station, Bhavanisagar 77.13333 11.68333 TRUE Cambisols 7.41 NA 6.44678 NA NA NA NA 0.47 NA 297 56.9 DTPA 7.16 6.4
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 5960 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 29.250000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 5960 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 32.250000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 7300 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 31.750000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 8400 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 35.000000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 8730 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 33.000000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 9400 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 36.500000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 3910 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 25.250000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 3910 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 27.250000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 5270 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 27.500000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 5270 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 29.500000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 6560 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 29.250000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 6560 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 33.000000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 7920 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 30.750000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2016 2016 NA FALSE control maize grain 8620 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 34.500000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.84 NA 6.84152 34.17 50.98 14.85 clay NA NA 0.220 NA NA Olsen 11.50 1.9
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 4460 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 27.000000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 5320 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 28.500000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 5320 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 28.500000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2
Abo-Marzoka et al., 2018 al-Gemmiza Agricultural Research Station-2017 2017 NA FALSE control maize grain 5960 NA TRUE 0.0 0.00 0.00 NA NA FALSE NA TRUE NA unknown NA NA NA 29.250000 NA Egypt al-Gemmiza Agricultural Research Station 31.02722 30.88333 TRUE Cambisols 7.95 NA 6.94250 34.23 51.17 14.60 clay NA NA 0.233 NA NA Olsen 8.60 2.2


The observations were made at 120 locations. We have coordinates for 109 of these locations. 20 records do not have coordinates.


The standardization script emits the following non-compliance warnings.

type message
metadata missing values in treatment variable Zn_fertilizer
metadata missing values in treatment variable Fe_fertilizer
unknown variables soil_Zn_method
NA values longitude, latitude
out of bounds N_fertilizer (0, 655), grain_Zn (3.88, 282.397), grain_Fe (4.5, 186), grain_protein (0.1, 22.45), grain_N (1.22, 3.85), soil_N (0.005, 2.4), soil_P (1.3, 426), soil_K (0.11, 7800)
yield_isfresh yield_isfresh must be set to TRUE or NA if yield_moisture is NA
duplicates duplicate records detected

The overall quality of the dataset, given the completeness of required variables was 6.9 on a scale of 10. See the table below

variable completeness (%)
planting_date 77.9
harvest_date 0.0
crop 100.0
variety 0.0
N_fertilizer 100.0
P_fertilizer 100.0
K_fertilizer 100.0
irrigated 52.8
latitude 82.4
longitude 82.4
location 98.4
adm 0.0
yield 100.0


The data are further summarized in the table below.

Variable Stats / Values Freqs (% of Valid) Graph Missing
reference [character]
1. Manzeke et al. 2014
2. Abo-Marzoka et al.,
3. Fahad et al. 2015
4. Abunyewa et al., 200
5. Paramasivan et al.,
6. Gharibi et al. 2016
7. Mohsin et al 2014
8. El_Metwaly et al. 20
9. Manjulatha, 2013
10. Umesh et al., 2014
[ 96 others ]
84(3.6%)
80(3.4%)
80(3.4%)
78(3.3%)
74(3.1%)
72(3.1%)
66(2.8%)
60(2.5%)
60(2.5%)
58(2.5%)
1643(69.8%)
 0 (0.0%)
trial_id [character]
1. Kamatchipuram villag
2. Faisalabad-NA
3. Perambalur-NA
4. Hwedza-2010
5. Hwedza-2011
6. Karimnagar-2011
7. al-Gemmiza Agricultu
8. al-Gemmiza Agricultu
9. Islamabad-2010
10. Islamabad-2011
[ 146 others ]
48(2.0%)
46(2.0%)
46(2.0%)
42(1.8%)
42(1.8%)
42(1.8%)
40(1.7%)
40(1.7%)
40(1.7%)
40(1.7%)
1929(81.9%)
 0 (0.0%)
planting_date [integer]
Mean (sd) : 2012 (5)
min ≤ med ≤ max:
1997 ≤ 2013 ≤ 2022
IQR (CV) : 6 (0)
 24 distinct values 520 (22.1%)
on_farm [logical]
All NA's
 2355 (100.0%)
is_survey [logical] 1. FALSE
2355(100.0%)
 0 (0.0%)
treatment [character]
1. control
2. (Empty string)
3. 4 splits: 30:40:30:2
4. Control
5. foliar ;EgyptianClov
6. foliar ;Wheat
7. foliar at milkystage
8. foliar at tasseling
9. soil application of
10. soil application of
[ 558 others ]
905(38.4%)
336(14.3%)
18(0.8%)
13(0.6%)
12(0.5%)
12(0.5%)
10(0.4%)
10(0.4%)
10(0.4%)
10(0.4%)
1019(43.3%)
 0 (0.0%)
crop [character] 1. maize
2355(100.0%)
 0 (0.0%)
yield_part [character] 1. grain
2355(100.0%)
 0 (0.0%)
yield [numeric]
Mean (sd) : 5686.8 (2590.9)
min ≤ med ≤ max:
270 ≤ 5680 ≤ 17780
IQR (CV) : 3706 (0.5)
 1036 distinct values 0 (0.0%)
yield_moisture [logical]
All NA's
 2355 (100.0%)
fertilizer_used [logical] 1. TRUE
2355(100.0%)
 0 (0.0%)
N_fertilizer [numeric]
Mean (sd) : 111.9 (100.8)
min ≤ med ≤ max:
0 ≤ 100 ≤ 655
IQR (CV) : 200 (0.9)
 59 distinct values 0 (0.0%)
P_fertilizer [numeric]
Mean (sd) : 53 (61.6)
min ≤ med ≤ max:
0 ≤ 40 ≤ 239.9
IQR (CV) : 75 (1.2)
 57 distinct values 0 (0.0%)
K_fertilizer [numeric]
Mean (sd) : 36.7 (48)
min ≤ med ≤ max:
0 ≤ 0 ≤ 207
IQR (CV) : 74 (1.3)
 50 distinct values 0 (0.0%)
Zn_fertilizer [numeric]
Mean (sd) : 5.4 (9.8)
min ≤ med ≤ max:
0 ≤ 1.2 ≤ 90
IQR (CV) : 7.4 (1.8)
 76 distinct values 1206 (51.2%)
Fe_fertilizer [numeric]
Mean (sd) : 2.1 (5.5)
min ≤ med ≤ max:
0 ≤ 0.1 ≤ 30
IQR (CV) : 2.5 (2.6)
 9 distinct values 2276 (96.6%)
OM_used [logical]
1. FALSE
2. TRUE
2289(97.2%)
66(2.8%)
 0 (0.0%)
OM_type [character]
1. (Empty string)
2. farmyard manure
3. leaf litter
4. none
5. sludge
6. unknown
910(38.6%)
238(10.1%)
18(0.8%)
1176(49.9%)
10(0.4%)
3(0.1%)
 0 (0.0%)
OM_amount [numeric]
Mean (sd) : 6 (5.8)
min ≤ med ≤ max:
0 ≤ 5 ≤ 33.6
IQR (CV) : 10 (1)
 10 distinct values 2289 (97.2%)
inoculated [logical]
1. FALSE
2. TRUE
134(5.7%)
2221(94.3%)
 0 (0.0%)
irrigated [logical]
1. FALSE
2. TRUE
886(71.2%)
358(28.8%)
 1111 (47.2%)
land_prep_method [character]
1. (Empty string)
2. none
3. reduced tillage
4. tillage
5. unknown
585(24.8%)
77(3.3%)
28(1.2%)
782(33.2%)
883(37.5%)
 0 (0.0%)
rain [numeric]
Mean (sd) : 807.7 (511.7)
min ≤ med ≤ max:
55 ≤ 750 ≤ 3000
IQR (CV) : 309 (0.6)
 32 distinct values 1651 (70.1%)
grain_N [numeric]
Mean (sd) : 2.3 (0.8)
min ≤ med ≤ max:
1.2 ≤ 2.1 ≤ 3.9
IQR (CV) : 1.6 (0.4)
 84 distinct values 2260 (96.0%)
grain_Fe [numeric]
Mean (sd) : 57.3 (38.4)
min ≤ med ≤ max:
4.5 ≤ 56.8 ≤ 186
IQR (CV) : 52.3 (0.7)
 189 distinct values 2011 (85.4%)
grain_Zn [numeric]
Mean (sd) : 34.6 (29.1)
min ≤ med ≤ max:
3.9 ≤ 26.8 ≤ 282.4
IQR (CV) : 17 (0.8)
 825 distinct values 511 (21.7%)
grain_protein [numeric]
Mean (sd) : 10.4 (3.6)
min ≤ med ≤ max:
0.1 ≤ 10 ≤ 22.4
IQR (CV) : 3.4 (0.3)
 137 distinct values 2205 (93.6%)
country [character]
1. India
2. Pakistan
3. Egypt
4. Zimbabwe
5. Iran
6. Ghana
7. China
8. Bangladesh
9. Malawi
10. Kenya
[ 12 others ]
789(33.5%)
454(19.3%)
314(13.3%)
191(8.1%)
100(4.2%)
78(3.3%)
63(2.7%)
57(2.4%)
42(1.8%)
37(1.6%)
230(9.8%)
 0 (0.0%)
location [character]
1. Faisalabad
2. Islamabad
3. Hwedza
4. Karnataka
5. al-Gemmiza Agricultu
6. Benha University
7. New Delhi
8. Cairo University
9. Karimnagar
10. Nyankpala
[ 96 others ]
160(6.8%)
95(4.0%)
91(3.9%)
82(3.5%)
80(3.4%)
72(3.1%)
61(2.6%)
60(2.5%)
60(2.5%)
51(2.2%)
1543(65.5%)
 0 (0.0%)
geo_from_source [logical]
1. FALSE
2. TRUE
394(16.7%)
1961(83.3%)
 0 (0.0%)
soil_type [character]
1. Cambisols
2. Vertisols
3. Calcisols
4. Luvisols
5. Acrisols
6. Regosols
7. Fluvisols
8. (Empty string)
9. Arenosols
10. Gleysols
[ 9 others ]
644(27.3%)
377(16.0%)
299(12.7%)
255(10.8%)
176(7.5%)
123(5.2%)
111(4.7%)
99(4.2%)
51(2.2%)
49(2.1%)
171(7.3%)
 0 (0.0%)
soil_pH [numeric]
Mean (sd) : 7.5 (1)
min ≤ med ≤ max:
4.4 ≤ 7.9 ≤ 8.7
IQR (CV) : 0.7 (0.1)
 50 distinct values 1233 (52.4%)
soil_pH_KCl [logical]
All NA's
 2355 (100.0%)
soil_pH_CaCl2 [numeric]
Mean (sd) : 6.6 (1.2)
min ≤ med ≤ max:
3.7 ≤ 6.9 ≤ 8.4
IQR (CV) : 1.6 (0.2)
 87 distinct values 469 (19.9%)
soil_sand [numeric]
Mean (sd) : 51.6 (22.4)
min ≤ med ≤ max:
19.7 ≤ 49 ≤ 94
IQR (CV) : 40.1 (0.4)
 48 distinct values 1359 (57.7%)
soil_clay [numeric]
Mean (sd) : 24.3 (16.1)
min ≤ med ≤ max:
0 ≤ 19 ≤ 53.2
IQR (CV) : 24 (0.7)
 51 distinct values 1316 (55.9%)
soil_silt [numeric]
Mean (sd) : 50.6 (38.3)
min ≤ med ≤ max:
2 ≤ 34.7 ≤ 100
IQR (CV) : 85.2 (0.8)
 49 distinct values 836 (35.5%)
soil_texture [character]
1. (Empty string)
2. clay
3. clay loam
4. loam
5. loamy sand
6. sand
7. sandy clay
8. sandy clay loam
9. sandy loam
10. silt
11. silty loam
836(35.5%)
259(11.0%)
5(0.2%)
191(8.1%)
283(12.0%)
44(1.9%)
35(1.5%)
6(0.3%)
109(4.6%)
523(22.2%)
64(2.7%)
 0 (0.0%)
soil_SOM [numeric]
Mean (sd) : 1.7 (2.1)
min ≤ med ≤ max:
0.1 ≤ 1 ≤ 12.1
IQR (CV) : 1.2 (1.3)
 73 distinct values 1038 (44.1%)
soil_SOC [numeric]
Mean (sd) : 0.8 (0.9)
min ≤ med ≤ max:
0 ≤ 0.5 ≤ 6.3
IQR (CV) : 0.6 (1.1)
 88 distinct values 811 (34.4%)
soil_N [numeric]
Mean (sd) : 0.2 (0.3)
min ≤ med ≤ max:
0 ≤ 0.1 ≤ 2.4
IQR (CV) : 0.2 (1.7)
 36 distinct values 1566 (66.5%)
soil_K [numeric]
Mean (sd) : 219.9 (683.4)
min ≤ med ≤ max:
0.1 ≤ 174.5 ≤ 7800
IQR (CV) : 166.5 (3.1)
 72 distinct values 1207 (51.3%)
soil_P [numeric]
Mean (sd) : 18.9 (53)
min ≤ med ≤ max:
1.3 ≤ 8.3 ≤ 426
IQR (CV) : 8.8 (2.8)
 80 distinct values 994 (42.2%)
soil_P_method [character]
1. (Empty string)
2. AB-DTPA
3. Bray
4. DTPA
5. Mehlich
6. Mehlich 3
7. Olsen
8. P-Olsen
9. Resin
667(28.3%)
71(3.0%)
236(10.0%)
34(1.4%)
10(0.4%)
43(1.8%)
1240(52.7%)
38(1.6%)
16(0.7%)
 0 (0.0%)
soil_Fe [numeric]
Mean (sd) : 20.5 (24.9)
min ≤ med ≤ max:
0.7 ≤ 8.8 ≤ 133
IQR (CV) : 36.6 (1.2)
 40 distinct values 1604 (68.1%)
soil_Zn [numeric]
Mean (sd) : 2 (3.9)
min ≤ med ≤ max:
0 ≤ 0.9 ≤ 28
IQR (CV) : 1.4 (2)
 85 distinct values 373 (15.8%)