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.

PENGARUH PUPUK HAYATI DENGAN KOMPOSISI MIKROORGANISME YANG BERBEDA TERHADAP PERTUMBUHAN TANAMAN

Biofertilizer can be used to replace chemical fertilizer so that soil quality is maintained and soil pollution can be avoided. The study aimed to determine the effect of biofertilizers with different compositions of microorganisms on the growth of maize plants. The research was carried out in a greenhouse. Maize plants were fertilized by two kinds of biofertilizers with different compositions of microorganisms. The first biofertilizer contained Azotobacter sp, Azospirillum sp, Rhizobium sp, Trichoderma sp, and Lactobacillus sp, and the second biofertilizer contained Strenotrophomonas sp. and Paenibacillus polymyxa. As controls, maize plants were fertilized by sterilized those biofertilizers. The results showed that the second biofertilizer increased the dry weight of the maize plant. Meanwhile, the first biofertilizer did not increase it. Several things must be considered in the application of biofertilizers, such as the composition of microorganisms, type of plant, level of fertilization, and the method of applying fertilizer to the plant.

Replacing 30 % chemical fertilizer with organic fertilizer increases the fertilizer efficiency, yield and quality of cabbage in intensive open-field production

ABSTRACT: The combined application of chemical fertilizer and organic fertilizer is an effective way to improve soil fertility, crop yield and quality. In this study, a field experiment was conducted to evaluate the yield, quality and fertilizer use efficiency of cabbage (Brassica oleracea var. capitata L.) grown under different ratios of organic fertilizer replacing chemical fertilizer at a rate of 225 kg N ha-l in 2019 and 2020. The fertilizer treatments included N0 (non nitrogen fertilizer), CK (only compound fertilizer was applied, N:P:K=15.0 %:6.5 %:12.4 %), T1, T2 and T3 (organic fertilizer replaced 15 %, 30 % and 45 % chemical fertilizer, respectively), and T4 (total nutrient input was reduced by 10 % under T2). Results showed that T2 had the highest marketable yield and fertilizer use efficiency, as well as the best quality. The marketable yield, vitamin C content, soluble sugar content, REN (apparent uptake efficiency of fertilizer N) and AEN (agronomic N use efficiency) of T2 increased by 32.2 %, 14,9 %, 5.5 %, 97. % and 55.6 %, respectively, in contrast, the crude fibers decreased by 34.0 %, compared with CK in the two years. In addition, T4 guaranteed the yield and moderately improved the quality of cabbage, compared with CK. Therefore, we can alternatively apply fertilization according to the purpose of capturing the highest yield or properly declining fertilizer to sustain soil texture and productivity.

Effects of Chemical Fertilizer, Fym and Bio-Inoculants On Nutrient Content, Uptake and Quality of Wheat (Triticum Aestivum L.)

Effects of different levels of chemical fertilizer, farmyard manure (FYM) and bio-inoculants on nutrient content, uptake and quality parameter of wheat were studied. Results indicated that increasing levels of chemical fertilizer, FYM and bio-inoculants significantly enhanced nutrient content and uptake by wheat, while quality parameters of wheat showed significant results with bio-inoculants application. Maximum N, P and K content and their uptake in grain (80.3, 11.07 and 25.29%, respectively) and straw (32.18, 7.14 and 95.92%, respectively) were noticed with 100% NPK over control. Application of FYM @ 10 t/ha significantly increased nutrient content (NPK) in grain and straw and their uptake over the control. The total N, P and K uptake by wheat were found to be maximum 80.97, 12.68 and 86.10 kg/ha, respectively with the application of FYM over control. Combined use of fertilizer levels and FYM, and combined use of fertilizer levels and bio-inoculants significantly increased the nutrient uptake by wheat. Bangladesh J. Bot. 50(4): 1109-1117, 2021 (December)