Table 3.

Results of the regression analysis.

Dependent variable:	Equation (1) Nitrate	Equation (2) Nitrate	Equation (3) Nitrate	Equation (4) Nitrate	Equation (5) Nitrate	Equation (6) Nitrate
Precip	−0.838***	−0.649**	−0.274***	−0.286***	−2.287***	−3.546***
Temp	−0.635*	−1.022***	−0.257***	−0.246***	−1.310***	−1.294***
Landcover_grassland	−19.91**
Landcover_grassland2	27.06**
Landcover_cropland	11.73
Landcover_cropland2	40.83***
Landcover_buildings	−18.12
Landcover_buildings2	41.29*
Landcover_forest	44.91***
Landcover_forest2	−51.68***
fwc	−71.26***	−104.5***			−203.3***	−202.7***
vs	0.445***	0.119			0.164	0.175
Farming_system		2.949*			6.149***	5.708***
Landuse_oilseed & protein		65.60*
Landuse_forage		24.21
Landuse_cereal & maize		24.61***
Landuse_row crops & veg		56.63**
Landuse_grassland		−15.94***
Nbal			0.0347***		0.0654***	−0.0275
Fert				0.0350***
Withd				−0.0261**
Prop_AL					18.36***	18.28***
Precip*Nbal						0.0366**
Constant	43.27***	60.39***	20.17***	20.59***	95.52***	98.94***
Observations	14,169	7036	4811	4811	4423	4423
Adjusted R-squared	0.289	0.297	0.949	0.949	0.240	0.242
F-test	F(12, 1205) = 51.56	F(10, 1041) = 28.11	F(3, 3689) = 12.59	F(4, 3688) = 9.77	F(7, 1044) = 42.65	F(8, 1044) = 39.45
	Prob > F = 0.0000	Prob > F = 0.0000	Prob > F = 0.0000	Prob > F = 0.0000	Prob > F = 0.0000	Prob > F = 0.0000

*p < 0.1, **p < 0.05, ***p < 0.01.

The F-test tests whether all regression coefficients are jointly equal to zero.