Publication: Effects of nitrogen and phosphorus on shoots and roots biomass of Brachiaria grasses in low fertility soils of North western Kenya
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2016-09-14
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SIDA
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CABI Digitral Library
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Abstract
One of the major constraints to forage production in north western highlands of Kenya, is low soil fertility. The objective of this study was to assess the influence of nitrogen (N) and phosphorus (P) on growth and biomass production of Brachiaria grasses. Seven Brachiaria cultivars: Brachiaria brizantha cvs. Marandu, MG4, Piata, Xaraes, B. decumbens cv. Basilisk, B. hybrid cv. Mulato II and B. humidicola cv. Llanero were compared with two commonly grown forages, Rhodes grass and Napier grass cv. Kakamega 1. The treatments were tested in a split plot arrangement in a randomized complete block design with two rates of NP fertilizer, 0 and 40 kg P ha-1 applied at planting and 50 kg N ha-1 as a seasonal top-dress assigned to the main plot and the grass varieties as subplots. Shoots biomass was determined 14 weeks after seedlings emergence (WAE) and subsequent sampling done after every eight weeks. Roots biomass was assessed from 0-15 and 15 - 30 cm depths at 22, 46 and 80 WAE. During the wet season, the shoots biomass was significantly influenced by NP fertilizer (p = 0.05) and cultivars (p=0.001), but no significant interaction effects occurred. Fertilized grasses yielded 17% more shoots biomass than the unfertilized grasses. Basilisk, Marandu and Xaraes had the highest biomass yields (8.6 – 11.3 t ha-1) and were higher (p = 0.05) than Rhodes grass, and also the other Brachiaria cultivars. Roots biomass was higher at the 0 - 15 cm depth at all sampling times and decreased with depth. Brachiaria cultivars had high roots biomass than Napier and Rhodes grass. Fertilizer response to roots biomass was only noted at 22 WAE only. Basilisk and MG4 are the best Brachiaria options for the north western highlands due to their higher shoots and roots biomass yields.Key words: Dry and wet season, fertilizer, soil quality, shoots biomass.
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Dry and wet season, Fertilizer, Soil quality, Shoots biomass.