Table 3.
P-values and significance of year-to-year variation in maize grain yield and mineral content between the 2018–19 and 2019–20 conservation agriculture trials.
| Treatment | Yield | Carbon | Nitrogen | Iron | Potassium | Magnesium | Manganese | Phosphorus | Zinc | Selenium |
|---|---|---|---|---|---|---|---|---|---|---|
| T1 | 0.008** | 0.018* | 0.766 | 0.020* | 0.384 | 0.353 | 0.202 | 0.339 | 0.948 | 0.284 |
| T2 | 0.019* | 0.024* | 0.997 | 0.453 | 0.328 | 0.772 | 0.764 | 0.176 | 0.020* | 0.496 |
| T3 | 0.011* | 0.042* | 0.085 | 0.626 | 0.744 | 0.954 | 0.521 | 0.653 | 0.349 | 0.325 |
| T4-5 | 0.035* | 0.050 | 0.234 | 0.775 | 0.020* | 0.023* | 0.007** | 0.004** | 0.020* | 0.002** |
| T6 | 0.065 | 0.025* | 0.082 | 0.136 | 0.198 | 0.203 | 0.033* | 0.022* | 0.051 | 0.123 |
| T7 | 0.095 | 0.010* | 0.900 | 0.418 | 0.216 | 0.101 | 0.057 | 0.067 | 0.075 | 0.405 |
| T8 | 0.039* | 0.391 | 0.587 | 0.401 | 0.108 | 0.717 | 0.802 | 0.508 | 0.106 | 0.590 |
* and **
mean significant at 0.05 and 0.01, respectively, paired two-tailed t-test. Treatments: T1 = conventional agriculture; sole maize. T2 = conservation agriculture (CA); basin sowing; sole maize. T3 = CA; dibble stick sowing; sole maize. T4–5 = CA; dibble stick sowing; maize-cowpea rotation. T6 = CA; dibble stick sowing; maize-pigeon pea intercrop. T7 = CA; dibble stick sowing; maize-cowpea intercrop. T8 = CA; dibble stick sowing; maize-velvet bean intercrop.