This study characterized wheat straw feeding practices in smallholder farms using cross sectional survey and the results informed the design of an experiment to improve the nutritive value of wheat straw with urea and yeast culture treatment. Three diets tested in 49 days' feeding trial were farmers' rainy season feeding practice (FP), addition of urea to wheat straw at the time of feeding (USWS), and 14 days' incubation of straw with urea (UTWS). Yeast culture (15 g/day) was mixed with commercial dairy meal at the point of feeding. Survey data identified farmers' strategies in utilizing crop residues of which most important were improving storage facility (77.6%), adding molasses (54.5%), and buying a shredding machine (45.1%). On-farm feeding trial showed that intake was higher for UTWS than ( < 0.05) for USWS while milk yield was higher with FP than ( < 0.005) with UTWS or USWS but not different ( ≥ 0.05) between UTWS and USWS. Results imply that farmers feeding practices of crop residues may be improved for dairy cows' feeding and therefore UTWS could be used to support maintenance and milk production during dry season. Improving farmers feed storage facilities and training on incubation of wheat straw for dairy cattle feeding were recommended.

The study evaluated the effects of feeding urea treated/supplemented wheat straw-based diets with addition of yeast culture (YC) as a dry season feed for dairy cows. Wheat straw diets with 3.6% urea and 5.8% molasses were formulated to upgrade nonprotein nitrogen levels and fibre degradation in the rumen. Yeast culture was included at 0 and 10 g/cow/day in mixer with commercial dairy meal to improve on fibre degradation and milk yield. Two experiments were conducted. Firstly, an in sacco dry matter degradability (DMD) trial with three steers in a completely randomized design (CRD) with a 3 × 2 factorial arrangement to determine the effects on intake and rumen degradation parameters. Secondly, feeding trial with 18 lactating cows in a 3 × 2 factorial arrangement at two levels of yeast culture (0 and 10 g/cow/day) and three types of urea interventions: No intervention (WS); addition of urea to straw at the time of feeding (USWS); and 7 days incubation of straw with urea (UTWS). Yeast cultures addition had no effect on rumen pH and NH3-N, but urea intervention showed an effect on rumen pH with USWS being lowest (p < 0.05). Both urea interventions and yeast culture addition had no effect (p > 0.05) on dry matter intake, milk yield, and milk composition but they increased (p < 0.05) propionate yields.

Aims: The study determined the effect of legumes in short term crop rotation (cereal – legumes cropping systems) on nitrogen use efficiency of wheat. Study Design: A randomized complete block design (RCBD) was used in a split-split-plot arrangement replicated three times. Three factors evaluated included water harvesting (WH), crop rotation (CR) and soil fertility management (SFM). The data obtained were subjected to an analysis of variance (ANOVA) using Genstat statistical package while the mean separation was performed using least significance differences (P =.05). Place and Duration of Study: The trial was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO) fields based in Njoro for three years between 2014 and 2016 during rainy seasons. Methodology: The treatments consisted of four pre-crops in the rotation systems (CR1 = Dolichos lablab (L. purpureus) as a pre-crop; CR2 = Green pea (Pisum sativum) as a pre-crop; potato (Solanum tuberosum) as a pre-crop; and CR4 = continuous wheat (Triticum aestivum), two water harvesting (WH) strategies (WH = flat beds; and WH= tied ridges) and  six soil fertility management (SFM) strategies (SFM1 = untreated control; SFM2 = FYM at 5 t ha-1;  SFM3 = Green manure (Leucaena trichandra) at 2.5 t ha-1; SFM4 =  inorganic source at 25 kg N ha-1; SFM5 = inorganic source at  50 kg N ha-1; and SFM6 = Inorganic source at 75 kg N ha-1).. Results: The results revealed that the value of NUE significantly (p < 0.001) increased when P. sativum and L. purpureus preceded wheat in the short term crop rotation system.  The value of NUE increased by 39% and 44%, when wheat was preceded L. purpureus and P. sativum, respectively, relative to S. tuberosum.  Under continuous wheat, NUE value was increased by 54.17% relative to potato as a pre-crop. Overall, the contribution of legumes (L. purpureus and P. sativum) as precursor crops was greater than those observed with potato and wheat as pre-crops.

Aims: The study determined the effect of soil fertility management (inorganic and organic N sources) and short term crop rotation (cereal – legumes cropping systems) on water use efficiency of wheat in high potential areas. Study Design: A randomized complete block design was used with split-split-plot arrangement replicated three times. Three factors evaluated included water harvesting (WH), crop rotation (CR) and soil fertility management (SFM). The data obtained were subjected to an analysis of variance (ANOVA) using Genstat statistical package while the mean separation was performed using least significance differences (P =.05). Place and Duration of Study: The trial was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO) fields based in Njoro for three years between 2014 and 2016 during rainy seasons. Methodology: Water harvesting was evaluated at consisted of flat beds (WH1) and tied ridges (WH2), crop rotation was tested at four levels comprising of Wheat- Dolichos lablab (Lablab purpureum)-Wheat- L. purpureum (CR1); Wheat-Greenpea (P. sativum) –Wheat (Triticum aestivum L)- P. sativum (CR2); T. aestivum L-potato- P. sativum –Potato (Solanum tuberosum) (CR3); and Wheat-Wheat-Wheat-Wheat) (CR4). Six different soil fertility management (SFM) strategies evaluated included SFM1 = untreated control; SFM2 = Farm Yard Manure at 5 t ha-1; SFM3 = Green manure (L.eucaena triachandra) at 2.5 mt ha-1; SFM4 = Calcium Ammonium Nitrate (CAN) at 25 kg N ha-1; SFM5 = Calcuim Ammonium Nitrate at 50 kg N ha-1; and SFM6 = Ammonium Nitrate (CAN) at 75 kg N ha-1. The Water harvesting (WH) and SFM were fixed on the same plot at the form and rate for the entire period of the study while crops were rotated between seasons. Water use efficiency was derived as a ratio of water use and grain yield and biomass. Results: Results revealed significant (P =.05) effect of crop rotation and soil fertility management on water use efficiency. However, water harvesting did not influence. While interaction of CR and SFM significantly (P =.05) influenced WUE and grain yield. Significant influence was also observed on WUE due to an interaction between WH and SFM. Dolichos lablab (L. purpureum) and green pea as pre-crops resulted in higher yield than when potato was the pre-crop and continuous wheat.  Use of inorganic N fertilizer with L. purpureum as a pre-crop resulted in higher grain yield than all other soil fertility management strategies evaluated. In conclusion, the use of green pea as a pre-crop during the short rain followed by wheat in long rains is a beneficial crop rotation systems and a climate smart strategy. In addition, organic N sources should be recommended for sustainable wheat production because it will positively influence the accumulation and slow release of soil moisture for increased water use efficiency.