Measuring and predicting soil moisture conditions for trafficability

Figures & data

Figure 1. Setup of Percostation and sensors (Ader LLC) in May, 2013 (photo by E. Reintam).

Table 1. Average soil properties and standard error of the values of the experimental site.

Properties		Soil depth (cm)
		10	25	45	70
Soil dry bulk density (Mg m^−3)	Field	1.35 ± 0.04	1.70 ± 0.02	1.62 ± 0.03	1.79 ± 0.05
	Grassland	1.51 ± 0.05	1.66 ± 0.04	1.68 ± 0.07
Water permeability (cm d^−1)	Field	157 ± 35.2	134 ± 32.4	31 ± 8.3	42 ± 9.1
	Grassland	286 ± 45.5	113 ± 18.5	36 ± 6.0	–
Maximum water-holding capacity (%)	Field	32 ± 0.42	25 ± 0.26	23 ± 0.18	22 ± 0.17
	Grassland	26 ± 0.21	24 ± 0.20	22 ± 0.17	–
Plastic limit (%)		22 ± 0.17	23 ± 0.18	27 ± 0.20	26 ± 0.14
Liquid limit (%)		30 ± 0.24	29 ± 0.22	40 ± 0.26	37 ± 0.21
Field capacity (%) at pF1.8		25 ± 0.19	24 ± 0.18	23 ± 0.18	24 ± 0.17
Dry soil water content (%) at pF2.3		12 ± 0.11	12 ± 0.10	14 ± 0.12	13 ± 0.10
Sand (%)		56 ± 2.8	58 ± 2.3	47 ± 2.7	49 ± 1.6
Silt (%)		34 ± 2.5	35 ± 1.8	30 ± 1.2	30 ± 2.2
Clay (%)		10 ± 0.6	6 ± 0.5	22 ± 1.2	20 ± 0.9

Figure 2. Measured soil volumetric water content (%, by Percostation) in different depths under field (Hordeum vulgare L.) and grassland, precipitations (mm) and calculated evapotranspiration by Alpatjev in 2013.

Figure 3. Measured soil volumetric water content (%, by Percostation) at different depths under field (Solanum tuberosum L.) and grassland, precipitations (mm) and calculated evapotranspiration by Alpatjev in 2014.

Figure 4. The correlation between measured and predicted soil volumetric moisture content (%) of upper 25 cm (average) of soil as an average of two years using the 2 h and daily step under cultivated (field) and grassland conditions. For daily predictions correlation is statistically significant (p < .05).

Table 2. Root mean square error of the models using the 2 h step or daily step interval to calculate water balance in the soil under field and grassland conditions in 2013 and 2014.

Month	Field				Grassland
	2 h step		Daily		2 h step		Daily
	2013	2014	2013	2014	2013	2014	2013	2014
May	2.49	1.13	0.39	0.35	0.93	3.15	1.17	0.16
June	3.28	1.65	0.43	0.77	3.93	3.94	0.63	0.67
July	3.23	2.27	0.56	0.43	5.98	3.05	0.92	0.61
August	7.13	2.21	0.52	0.34	4.86	6.01	1.70	0.46
September	2.46	1.22	0.33	0.14	3.49	1.41	1.30	0.21
October	3.07	2.91	0.53	1.16	3.25	2.62	0.84	0.21
November	4.36	0.12	0.25	0.31	3.26	1.57	0.52	0.20
All period	4.14	2.01	0.46	0.64	4.24	3.59	1.11	0.45