Demand-Driven Technologies for Sustainable Maize ... - IITA

112to farmers. Recommendations had also been made to the Ministryof Agriculture on the use of compound fertilizer to replace separateapplication of single super phosphate and sulphate of ammonia. Thiswould have the advantage of increased effi ciency in the use of plantnutrients and of considerable savings in transportation and handlingcosts. Also uniform application of fertilizers at moderately high rateswas found necessary to decrease variability in plant development andto measure the yield potential of the most productive varieties orhybrids.At Mokwa, research results showed that K application up to 90kg K2O/ha did not increase grain yield signifi cantly. In some othertrials no signifi cant response to K2O and Zn was found in the savannazones. However, application of K2O increased grain yield at Yandev(southern Guinea savanna, SGS), Ballah (SGS) and Kafi n Maiyaki(northern Guinea savanna, NGS). In another fertilizer trial, 30 to 60kg K2O/ha appeared optimum in the SGS while 2.5 kg Zn/ha gavemaximum grain yields at Ballah and Kafi n Maiyaki (Anon 1987). In atrial conducted for two years, there was no response to Zn at Yandev.In 1984, a linear response to N from 0 to 120 or 150 kg N/ha wasreported in some studies, although the application of more than 90kg N/ha did not result in signifi cant increases in grain yield in much ofthe savanna ecology. Ear length and some other traits also respondedlinearly to N fertilizer up to 120 kg/ha. Split N applications did not,however, appear to enhance maize grain yield. The requirements for Kand Zn increased with increased rainfall and clay content of the soil.Data on planting date trials at Samaru revealed signifi cant yieldreduction for delayed plantings after early June. Plant spacing trialsgave similar yields if plantings were one plant spaced 25 cm apart inthe rows, two plants on hills spaced 50 cm apart or three plants onhills spaced 75 cm apart. In another trial conducted at Kadawa, threevarieties SZV5, SZV3 and DMR-ESR-Y were compared with Bomolocal in four planting dates. The interaction between sowing dates andvarieties was not signifi cant. The highest yield was, however, obtainedwhen sown early in July. Decrease in grain yield associated withdelayed planting was minimized when the plant density was reduced.The delayed planting resulted in lower yield as well as lower attack byear rot organisms. Increasing plant density up to 100,000 plants/haat early planting increased grain yield and other yield parameters. Inanother trial, a 26% yield increase was obtained when plant densitywas increased from 25,000 to 50,000 plants/ha. In this particular study,increasing plant density beyond 50,000 plants/ha had no appreciableeffect on grain yield.Early planting provided an escape to Striga attack because theStriga plants were just emerging when the maize had already