Table 1.
Summary of comparison of site-specific nutrient management (SSNM) to farmer practice (FFP) or state recommendation (state rec.).
| Source/s | Country (# of sites) | Production systemβ | Seasonα | Decision toolΨ | N rate (kg N ha−1) |
P rate (kg P ha−1) |
K rate (kg K ha−1) |
Grain yield (Mg ha−1) |
PFPNγ (kg grain kg−1 N) |
GRFℜ (USD ha−1) |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SSNM | FFP | State rec. | SSNM | FFP | State rec. | SSNM | FFP | State rec. | SSNM | FFP | State rec. | SSNM | FFP | State rec. | SSNM | FFP | State rec. | |||||
| Rice | ||||||||||||||||||||||
| Haefele et al. (2003) | Mali (3) | Irrigated | DS | FERRIZ + RIDEV | 121 | 156 | 16 | 20 | 17 | 0 | 6.0 | 6.1 | 51 | 39 | 3223 | 3223 | ||||||
| WS | FERRIZ + RIDEV | 172 | 128 | 33 | 20 | 141 | 0 | 7.9 | 7.0 | 47 | 55 | 4135 | 3757 | |||||||||
| Segda et al. (2005) | Burkina Faso (1) | Irrigated | DS | FERRIZ + RIDEV | 139 | 81 | 105 | 21 | 15 | 31 | 20 | 15 | 30 | 6.6 | 5.2 | 5.9 | 57 | 63 | 56 | 3544 | 2779 | 3122 |
| WS | FERRIZ + RIDEV | 116 | 76 | 82 | 21 | 17 | 31 | 20 | 16 | 30 | 6.3 | 5.2 | 5.5 | 54 | 68 | 67 | 3339 | 2804 | 2899 | |||
| Saito et al. (2015) | Senegal (1) | Irrigated | DS | NE | 141 | 150 | 18 | 14 | 34 | 0 | 6.9 | 5.8 | 49 | 38 | 3647 | 3061 | ||||||
| WS | NE | 118 | 161 | 14 | 24 | 10 | 0 | 8.7 | 6.4 | 74 | 40 | 4706 | 3397 | |||||||||
| Africa Rice | Ghana (1) | Irrigated | DS & WS | RA | 126 | 151 | 115 | 19 | 19 | 26 | 37 | 36 | 50 | 4.9 | 4.3 | 4.1 | 39 | 28 | 36 | 2575 | 2229 | 2121 |
| Maize | ||||||||||||||||||||||
| Masego (2013) | South Africa (3) | WS | SPAD (timing) | 26 | 58 | 42 | 42 | 4.0 | 3.8 | 171 | 1016 | 931 | ||||||||||
| Oyinbo (2019) | Nigeria (17) | NE | 133 | 60 | 25 | 8 | 48 | 15 | 5.3 | 2.1 | 40 | 34 | 1316 | 507 | ||||||||
| Balemi and Rurinda (2020) | Ethiopia (7) | Rainfed | WS | NE | 128 | 101 | 54 | 69 | 37 | 0 | 7.0 | 6.8 | 55 | 68 | 1737 | 1696 | ||||||
| Ethiopia (2) | Rainfed | WS | NE | 6.8 | 5.1 | |||||||||||||||||
| Rurinda et al. (2020) | Nigeria (14) | Rainfed | WS | NE | 110 | 120 | 15 | 26 | 12 | 50 | 3.9 | 3.9 | 35 | 33 | 978 | 931 | ||||||
| Ethiopia (5) | Rainfed | WS | NE | 120 | 111 | 22 | 30 | 26 | 0 | 6.8 | 6.8 | 57 | 61 | 1755 | 1765 | |||||||
| Tanzania (22) | Rainfed | WS | NE | 100 | 100 | 12 | 9 | 12 | 0 | 2.7 | 2.7 | 27 | 27 | 657 | 669 | |||||||
| Treatment Comparisonsδ | ||||||||||||||||||||||
| SSNM vs. State for rice | 6.3 | 5.7 | 50 | 50 | 3363 | 3024 | ||||||||||||||||
| SSNM vs. FFP for rice | 5.6 | 4.6 | 48 | 41 | 3068 | 2447 | ||||||||||||||||
| SSNM vs. State for maize | 4.8 | 4.6 | 68 | 43 | 1554 | 1464 | ||||||||||||||||
| SSNM vs. FFP for maize | 6.1 | 3.6 | 40 | 34 | 1316 | 507 | ||||||||||||||||
| Overall | 5.7 | 4.4 | 5.2 | 55 | 40 | 49 | 2373 | 2170 | 2111 | |||||||||||||
Production systemβ: is based on soil-water conditions as influenced by the climate in the area where the crops were grown
Seasonα: is the period of the year during which the particular crop is cultivated
Decision toolΨ: is the SSNM-based tool which provides fertilizer recommendation; RIDEV is used to simulate optimal timing of agronomic management actions; FERRIZ is based on QUEFTS model together with on-farm data; SPAD is SPAD chlorophyll meter; NE is Nutrient Expert; RA is RiceAdvise
PFPNγ: is partial factor of productivity of N; a measure of N use efficiency
GRF ℜ: is gross return above fertilizer cost, which is calculated as GRF = Gross return - Total fertilizer cost
Treatment Comparisonsδ: Means for comparisons between FFP or State rec. were not made across all the studies because some studies only compared SSNM to either FFP or State rec.