Use of Biochar-Compost for Phosphorus Availability to Maize in a Concretionary Ferric Lixisol in Northern GHANA

A pot experiment was conducted to investigate the effect of biochar-compost on availability of P for maize cultivation in a concretionary Lixisol of northern Ghana and residual soil characteristics thereof. Sawdust biochar was co-composted with kitchen waste and cow dung in various proportions. Four biochar-composts were selected based on their superior carbon and available P content, lower pH, and electrical conductivity (EC). These were amended to attain the standard phosphorus requirement (SPR) and half the SPR of the Lixisol. Triple superphosphate and (NH4)2 SO4 were, respectively, applied as inorganic fertilizer to meet the SPR and the average total nitrogen of the selected biochar-compost treatments. A control without any soil amendment was included. Maize was grown to tasseling (eight weeks) and shoot dry matter and P uptake determined. A 2.71 to 3.71-fold increase in P uptake led to a 1.51 to 2.33-fold increase in shoot dry matter in biochar-compost-amended soils over the control. Residual soil C, pH, and total and available P in the biochar-compost-amended soils were enhanced. Biochar-composts at half the SPR level produced maize with higher shoot dry matter than the equivalent inorganic amendment at full SPR.

274 Determination of phosphorus requirement of lactating sows based on 24-hour urinary phosphorus excretion

The objective was to determine phosphorus (P) requirement of lactating sows using 24-hour urinary P excretion as the response criteria. The underlying assumption was that urinary P remains low and constant until the requirements are met then increases as P consumption increases. Thirty-six crossbred PIC Camborough sows (parity 3 to 7) were randomly assigned to 1 of 6 corn-soybean-meal diets with increasing dietary total P (tP) levels (0.40, 0.48, 0.56, 0.64, 0.72, and 0.80%) and a constant calcium (Ca) to tP ratio (1.25:1). Diets were fed from breeding until the end of lactation. Urine and blood samples were collected on days 4 and 18 of lactation and analyzed for P and Ca concentrations. Data were analyzed using MIXED and NLIN procedures of SAS. Phosphorus requirements were estimated using a broken-line regression model. Plasma Ca (ranging from 12.1 to 10.3 mg/dL) was not affected by dietary treatments, and was maintained within the normal physiological range on day 4 and 18 of lactation. Plasma P (ranging from 2.9 to 6.4 mg/dL) linearly increased (P < 0.05) with increasing dietary tP levels on day 4 and 18 of lactation. Only sows fed the 0.40% tP diet failed to maintain plasma P concentrations within the normal physiological range. Clinical signs of P and Ca deficiencies were not observed. Differences in sow and litter performance among treatments were not detected. A nonlinear response of urinary P excretion to dietary P intake was observed. Based on a broken-line linear model fit to 24-hour urinary P excretion, minimum tP requirements of sows at day 4 and 18 of lactation were 0.47 and 0.54%, respectively. In conclusion, 24-hour urine P excretion provided sensitive criteria for estimates of tP requirements in lactating sows. Efforts to adjust heteroscedasticity for animals fed dietary P above the estimated requirement need further evaluation.

Mathematical model for the prediction of available phosphorus and calcium requirements for European quails of 16-36 days old

Were used 724 quails, with initial weight of 105.05±1.40g to determine the model requirements for European quails 16-36 days old. Were used 384 quails for the maintenance requirement experiment and 240 for the gain requirement experiment and the remaining 100 quails composed the birds of the comparative slaughter. Maintenance requirement: the treatments consisted of four levels of feed offerings (100, 75, 50 and 25% of consumption ad libitum) with four pens and four quails per pen for each climatic environment (18, 24 and 28ºC), being 192 quails for each nutrient under study. Gain requirement: the requirements of the studied nutrients for gain were determined from 240 quails, created and fed ad libitum, being 120 quails for each nutrient studied, that is, 30 quails were slaughtered at 21, 26, 31 and 36 days of age. The quails of the reference slaughter comprise the same as the experiment for determining the maintenance requirement. In conclusion. The prediction equations for estimating the requirements were: 1) Pr (mg/quail/day) = (27.029 + 1.5943 × T) × kg0.75 + 12.24 × WG, in which Pr is the phosphorus requirement, kg0.75 is metabolic weight (kg), WG is weight gain (g/quail/day). 2) Ca (mg/quail/day) = (158.93 - 5.187 × T) × kg0.75 + 23.66 × WG, in which Ca is the calcium requirement, kg0.75 is metabolic weight (kg), WG is weight gain (g/quail/day), T is temperature.