Accelerated soil-nitrifier activity and rapid nitrification are the cause of declining nitrogen-use efficiency (NUE) and enhanced nitrous oxide (NO) emissions from farming. Biological nitrification inhibition (BNI) is the ability of certain plant roots to suppress soil-nitrifier activity, through production and release of nitrification inhibitors. The power of phytochemicals with BNI-function needs to be harnessed to control soil-nitrifier activity and improve nitrogen-cycling in agricultural systems. Transformative biological technologies designed for genetic mitigation are needed, so that BNI-enabled crop-livestock and cropping systems can rein in soil-nitrifier activity, to help reduce greenhouse gas (GHG) emissions and globally make farming nitrogen efficient and less harmful to environment. This will reinforce the adaptation or mitigation impact of other climate-smart agriculture technologies.

The millet (Pennisetum glaucum)-based cropping systems that dominate the Sudano±Sahelian Zone of West Africa cannot, as they are currently practised, meet the growing food needs of the region. They must therefore be intensi®ed in a sustainable manner. The present study was initiated in 1986 and continued until 1996 to evaluate the eects of phosphorus (P) fertilization, tillage and rotation with sole cowpea (Vigna unguiculata) on an operational scale with two cropping systems, namely, sole millet and millet±cowpea intercropping. A randomized complete block design with four replications was used. The eects of P fertilization, ridging with animal traction and planting on ridges (AT), and rotation with sole cowpea increased the productivity of millet substantially in 10 of the 11 years. Based on the 11-year average, P fertilization alone improved grain yield by 52%, and AT with P fertilization improved grain yield by nearly 135%. Combining AT, P fertilization and the sole cowpea rotation resulted in a 200% increase in grain yield compared with the traditional system of production. Millet productivity did not show a signi®cant decline when intercropped with cowpea. Stability and relative stability analysis showed that the traditional system was more stable than the various agronomic packages, but had the least yield. Conversely, the agronomic package with the highest yield advantage over the traditional system was the least stable. A major portion of the annual variation in the environmental index for grain yield and total dry matter was attributed to the seasonal variation in rainfall and organic matter depletion. Organic matter levels declined linearly with years of cultivation. Signi®cant dierences were found in the rate of depletion between the various agronomic treatments tested. After 11 years, nearly 60% of the organic matter was depleted irrespective of the agronomic treatments.