Influence of Soil Fertility Management on Nitrogen Mineralization, Urease Activity and Maize Yield

For studying the effect of soil fertility management practices on N mineralization, urease activity and maize yield, replicated field trials were established in 2015 at Misamfu and Msekera agricultural research stations (ARS) representing two geo-climatic regions of Zambia. The soil at Msekera ARS is a sandy clay loam (SCL) from a Paleustult, while that at Misamfu is a loamy sand (LS) from a Kandiustult. The field trials had three categories of treatments namely legumes, traditional and conventional. The legumes group consisted of researcher-recommended legume-cereal intercrop systems of maize with Cajanus cajan, Crotalaria juncea and Tephrosia vogelii in combination with compound D (10% N, 20% P2O5, 10% K2O) and urea (46% N) at the recommended rate (200 kg ha-1) and half of the recommended rate (100 kg ha-1). Composted cattle manure and Fundikila, a special plant biomass management technique, were the inputs under the traditional category. The conventional category consisted of a treatment to which only chemical fertilizer was applied. Urease activity was determined in surface soil samples (0-20 cm) collected from the field trials after 3 years. For N mineralization, a laboratory incubation study was conducted over 13 weeks. For the laboratory incubation, an additional treatment to which no input was applied was included as control. Application of organic inputs significantly increased the potentially mineralizable N (No) by 127% to 256% on the LS and by 51% to 131% on the SCL in comparison to the control. Similarly, the cumulative N mineralized (Ncum) was twice or thrice higher where organic inputs had been applied in comparison to the control. The No followed the order traditional > legumes > conventional > control, while the mineralization rate constant (k) followed the order legumes > conventional > traditional > control on both soils. The rate of N mineralization was significantly higher on the LS than the SCL. Higher rates of chemical fertilizer resulted in high Ncum and higher maize yield. Maize yield was significantly and positively correlated to Ncum, but inversely correlated to the amount of applied N that was mineralized (%Nmin). Urease activity was stimulated by application of organic inputs and suppressed by higher rates of chemical fertilizers. The type of organic inputs; the rate of chemical fertilizers; and soil texture are factors influencing N mineralization and maize yield. Urease activity was largely influenced by the rate of chemical fertilizer, but not the type of organic inputs or soil texture

Effects of biochar and gypsum soil amendments on groundnut (Arachis hypogaea L.) dry matter yield and selected soil properties under water stress

The effects of amending soil with gypsum and biochar on groundnut chlorophyll concentration, water use efficiency (WUE), biomass yield and selected soil properties were investigated under water stress. Gypsum (CaSO4.2H2O) was applied at 0 and 200 kg/ha, groundnut shell biochar at 1, 2 and 4% w/w of soil, and water at 100, 70 and 40% of daily plant water requirement (PWR) as main, sub and sub-sub plots, respectively, in a split-split-plot design. Biochar neutralized the acid soil, significantly raising soil pH from 5 to 7.15 and increasing cation exchange capacity by 75%. Biochar amended at 1 and 2%, increased groundnut dry matter yield by 28%. The optimum biochar application rate for dry matter yield was 1.4% w/w. Biochar application at 4% and irrigation at 40% of PWR reduced the WUE by 45 and 50%, respectively. Chlorophyll concentration index was highest at 40% of PWR. The results suggest that biochar has potential to raise soil pH, increase moisture retention and improve crop performance. Applying water at 100% PWR can increase groundnut dry matter yields, while higher gypsum application rates may be required to affect crop performance

FarmLime Project Summary Report

This report summarises work funded by the Department for International Development Knowledge and Research programme, as part of the British Government’s programme of aid to developing countries. The ‘FarmLime: Low-cost lime for small-scale farming’ project (R7410) set out to investigate a way of improving the agricultural performance of small scale farms through the use of low-cost agricultural lime produced within the farming district using locally occurring dolomite. The main technical research phase (1999 to 2001) will be followed with a dissemination workshop phase(2002 to 2005)

Effects of hand-hoe tilled conservation farming on soil quality and carbon stocks under on-farm conditions in Zambia

Conservation farming (CF) has been promoted in Zambia since the 1980s. Despite long-term practice of CF in Zambia, its effect on soil fertility, including the storage of soil organic matter (SOM), on smallholder farms are inconclusive. Here, we assess the effect of CF as compared to conventional tillage on soil quality parameters on smallholder farms in the Eastern province (EP, 20 sites, two to six years of CF) and Central province (CP, 20 sites, four to twelve years of CF) in Zambia. Soils under CF (minimum tillage hoe basins, crop rotation and residue retention) were compared with adjacent conventional farms (hoe ridges in EP and overall digging or ridge splitting in CP). Only small differences were observed in the soil quality parameters between the CF basins and adjacent conventional plots after maximum 12 years since CF adoption. The concentration of soil organic carbon (%SOC) and carbon (C) stocks did not differ significantly between management practices, with C stocks in CF basins and conventional plots in EP amounting to 4.41 and 4.63 kg m−2, respectively, while this is 3.37 and 3.57 kg m−2, in CP. Likewise, the %SOC did not differ significantly between soils in the basins and in-between the basins. Both observations indicate that either the annual net accumulation of SOC is very small, or that on-farm surveys involve significant year-to-year changes in the position of the basins. However, the latter is not supported by plant available phosphorus (Bray P) data, which are significantly greater in CF basins than in-between them (12.7 vs 8.3 mg kg soil−1 in CP and 8.5 vs 5.2 mg kg soil−1 in EP), indicating significant Bray P accumulation in CF basins, due to annual fertilizer addition. Amounts of Bray-P in CF basins did not significantly differ from that under conventional management. Overall, our results show small differences in the soil quality parameters between the CF and conventional practices at smallholder farms after maximum 12 years since adoption of CF.Effects of hand-hoe tilled conservation farming on soil quality and carbon stocks under on-farm conditions in ZambiaacceptedVersio

Characterisation and evaluation of selected carbonate rock and gypsum resources for use in crop production in Zambia

No Abstract Available Journal of Science and Technology Special Edition 2004: 86-9

Effects of planting depth and water drop size on emergence and seedling Establishment of Sorghum [Sorghum bicolor(L) Moench]

No abstract availabl

Evaluation of the effectiveness of a new method of measuring the chemical reactivity of liming materials on two acid soils from Zambia

There is currently no quick available method for assessing chemical reactivity of liming materials used to neutralize soil acidity. This study was conducted to assess the effectiveness of a method developed to determine the chemical reactivity of liming materials. The reactivity of five conventional liming materials, biochar, charcoal and wood ash was determined using the method. Liming materials were applied to surface samples of two Ultisols at rates intended to neutralize exchangeable acidity. Physico-chemical and mineralogical properties of liming materials and soils were determined. Soils treated with the liming materials were incubated for 12 weeks in plastic containers using a soil: water ratio of 1:1. The pH and exchangeable acidity of the samples were measured every fortnight. The reactivity of the conventional liming materials was found to be strongly and positively (r = 0.99) correlated with their calcite contents, and strongly and negatively (r = -0.98) correlated with their dolomite contents. Strong positive linear relationships (R-2 >= 0.79, p = 0.79, p < .05) was observed between the reactivity and mean exchangeable acidity of the soils. Conventional liming materials were better than biochar and charcoal in neutralizing acidity. The new method was effective in predicting the ability of liming materials to neutralize exchangeable acidity and to raise the pH of acid soils. It can be used by farmers and lime producers to assess the reactivity of liming materials