Table 7 Coefficient signs following Randomized LASSO selection for each SPPs
Soil total NPK | Soil mineral nitrogen | Plant nutrient level | N2O emission | NPK availability | Potential CEC | Effective CEC | NUE | Mineral N leaching | |
|---|---|---|---|---|---|---|---|---|---|
Study location and Climate | |||||||||
Continent | ± | ± | + | + | + | ||||
Annual temperature | |||||||||
Annual precipitation | |||||||||
Experimental condition | |||||||||
Experimental design | – | ||||||||
Experimental duration | – | ± | + | ||||||
Biochar application rate | + | + | + | - | ± | + | – | ||
Biochar with fertilizer | |||||||||
Fertilizer application rate | – | – | ± | ||||||
Biochar with manure | |||||||||
Manure application rate | |||||||||
Biochar properties | |||||||||
Feedstock types | |||||||||
Pyrolysis temperature | + | – | |||||||
Soil status | |||||||||
Soil texture | – | + | |||||||
Soil pH | + | – | – | – | |||||
Soil minimum depth | |||||||||
Soil maximum depth | + | ||||||||
Fertilizer before biochar | |||||||||
Manure before biochar | |||||||||
Irrigation application | |||||||||
Tillage application | |||||||||
Publication status and bias | |||||||||
Publication year | + | – | + | - | |||||
Square root of effective sample size | + | + | + | + | + | + | |||