Impact of soil treatment with alkaline zinc carbonate on the quantity and quality of maize (Zea mays L.) yield

Our research conducted at the Department of Soil Management was aimed at investigating whether maize (Zea mays L.) would respond to a supply of zinc as a micro-element. We expected an increased yield and/or improvements in certain quality factors, such as a greater oil and starch contents. Soil fertilization experiments were performed with a basic zinc-carbonate active agent, under field conditions, in brown forest soil with clay illuviation, in a random block arrangement. Four iterations of the experiments were done in the vicinity of Zimány village in South-West Hungary. Maize served as our test crop. In 2010 we tested the first-year impact of the active agent, while in 2011 we evaluated its retard effect. In 2010 each of the examined quality attributes showed most improvement in response to the 100 kg ha-1 treatment, which corresponded to the largest dose applied in the study. Out of the examined yield elements the average values of the cob mass and the unfertilized cob length were greatest in 2011, because of the 25 kg ha-1 treatment, the lowest dose in the experiment, while with respect to the grain/cob ratio the 50 kg ha-1 treatment was found the most effective.

The influence of tillage and fertilizer on the flux and source of nitrous oxide with reference to atmospheric variation using laser spectroscopy

Nitrous oxide (N2O) is the third most important long-lived greenhouse gas and agriculture is the largest source of N2O emissions. Curbing N2O emissions requires understanding influences on the flux and sources of N2O. We measured flux and evaluated microbial sources of N2O using site preference (SP; the intramolecular distribution of 15N in N2O) in flux chambers from a grassland tilling and agricultural fertilization experiments and atmosphere. We identified values greater than that of the average atmosphere to reflect nitrification and/or fungal denitrification and those lower than atmosphere as increased denitrification. Our spectroscopic approach was based on an extensive calibration with 18 standards that yielded SP accuracy and reproducibility of 0.7 ‰ and 1.0 ‰, respectively, without preconcentration. Chamber samples from the tilling experiment taken ~ monthly over a year showed a wide range in N2O flux (0–1.9 g N2O-N ha−1 d−1) and SP (− 1.8 to 25.1 ‰). Flux and SP were not influenced by tilling but responded to sampling date. Large fluxes occurred in October and May in no-till when soils were warm and moist and during a spring thaw, an event likely representing release of N2O accumulated under snow cover. These high fluxes could not be ascribed to a single microbial process as SP differed among chambers. However, the year-long SP and flux data for no-till showed a slight direct relationship suggesting that nitrification increased with flux. The comparative data in till showed an inverse relationship indicating that high flux events are driven by denitrification. Corn (Zea mays) showed high fluxes and SP values indicative of nitrification ~ 4 wk after fertilization with subsequent declines in SP indicating denitrification. Although there was no effect of fertilizer treatment on flux or SP in switchgrass (Panicum virgatum), high fluxes occurred ~ 1 month after fertilization. In both treatments, SP was indicative of denitrification in many instances, but evidence of nitrification/fungal denitrification also prevailed. At 2 m atmospheric N2O SP had a range of 31.1 ‰ and 14.6 ‰ in the grassland tilling and agricultural fertilization experiments, respectively. These data suggest the influence of soil microbial processes on atmospheric N2O and argue against the use of the global average atmospheric SP in isotopic modeling approaches.

RESPON PRODUKSI KELAPA SAWIT DALAM PANENTUAN DOSIS OPTIMUM UREA DAN MOP PADA TANAH TYPIC PALEUDULT

Determination of the optimum dosage of urea fertilizer (source N) and MOP (source K) in oil palm producing (TM) plants through fertilization experiments in the field is very important because the plant needs for both types of fertilizers are relatively high. N-K fertilization trials on TM (aged 4-12 years) have been conducted at one location of PT.Salim Ivomas Pratama Tbk & Subs (in two gardens: Lubuk Raja Estate and / Balam Rumbia Estate) during the 1992-2000 time period. The urea and MOP fertilization treatments separately showed the response of FFB production by 22 and 50%, respectively (1995 - 2000). The interaction of urea and MOP is not real. The response curve of FFB production to urea and MOP doses showed that the optimum dosage in Typic Paleudult soil types for TM aged 7-12 years was 2.50 kg urea and 3.00 kg MOP / tree / year to achieve the production target of 28 tons of FFB / ha /year.To get the maximum fertilizing effect, fertilization must be done by using the type of fertilizer, the correct method and time of fertilization, and with fertilizer quality that is in accordance with specifications (for example SNI or Indonesian National Standard). An examination of the quality of fertilizers is important so that the company avoids multiple losses that have a large impact on production.

Enhanced efficiency of phosphorus fertilizer in soybean and maize

Soybeans and maize are the most cultivated crops in tropical soils and require large amounts of phosphate fertilizers. The use of enhanced-efficiency fertilizers is a promising technology to minimize losses of P by fixation in highly weathered tropical soils. The objectives of this study were to evaluate morphological characteristics, soybean P and boron foliar content, yield and agronomic efficiency of P fertilizer in response to P rates and sources in maize and soybean crops. Two P fertilization experiments with the sources Mono-ammonium Phosphate (MAP) and Policote coated MAP were carried out, one in maize (0, 20, 40, 80, 120 and 160 kg P2O5 ha-1) and another in soybean crop (0, 20, 40, 80 and 120 kg P2O5 ha-1). The morphological characteristics, soybean P and boron foliar content, yield and agronomic P fertilizer efficiency were evaluated. The results showed that maize and soybean morphological characteristics, as well as soybean foliar P and boron contents were not influenced by fertilization. P fertilization increased soybean yield. Policote coated MAP was more efficient than MAP (conventional fertilizer) to produce higher maize and soybean yields and higher agronomic efficiency of P use. For higher productivity, we recommend the dose of 102.9 kg P2O5 ha-1 of Policote coated MAP for soybean and 97.6 kg P2O5 ha-1 for maize.

Insights on nitrogen and phosphorus co-limitation in global croplands from theoretical and modelling fertilization experiments

Crossed fertilization additions are a common tool to assess nutrient interaction in a given ecosystem. Such fertilization experiments lead to the definition of nutrient interaction categories: e.g. simultaneous co-limitation, single resource response, etc. (Harpole et al., 2011). However, the implications of such categories in terms of nutrient interaction modeling are not clear. To this end, we developed a theoretical analysis of nitrogen (N) and phosphorus (P) fertilization experiments based on the computation of ratios between plant demand and soil supply for each nutrient. The theoretical analysis is developed following two mathematical formalisms of interaction: Liebig's law of minimum and multiple limitation hypothesis. As results of the theoretical framework, we defined the corresponding between most Harpole categories and the values of the limitation by each nutrient when considered alone in the control experiment (i.e. without additional nutrient supply). We showed that synergistic co-limitation could occur even using Liebig's formalism under certain conditions as a function of the amount of N and P added in fertilization experiments. We then applied our framework with global maps of soil supply and plant demand for croplands to achieve their potential yield. This allowed us to estimate the global occurrence of each limitation category, for each of the possible interaction formalism. We found that a true co-limitation could affect a large proportion of the global crop area (e.g. ~ 42 % for maize) if multiple limitation hypothesis is assumed. Our work clarifies the conditions required to achieve N and P co-limitation as function of the interaction formalism. Combined with compilation of field trials in cropland, our study would improve our understanding of nutrient limitation in cropland at the global scale.