Katalin Debreczeni

Long-term field experiments of the world

Long-term field experiments are indispensable sources of knowledge. They are vitally important in monitoring, understanding and proving the changes in soil fertility occurring as a result of long-term agrotechnical operations, first of all that of fertilization. Because of longevity, it is fairly costly to maintain them. Their scientific and practical value is, however, immeasurable and keeps growing with their age. The information concerning the land use can not be replaced by other means. The oldest long-term experiments that have run continuously since their foundation are 160-years-old now. They were established at Rothamsted in England by the Rothamsted Experimental Stations founder J. B. Lawes and J. H. Gilbert in 1843. The scientific work of J. von Liebig, the German chemist, who drew up the theory of the increase of soil fertility, has also contributed to the foundation of the Rothamsted Classic Experiments to a large extent. In those days heated discussions about nutrient recycling incited the experimentation and scientific investigation. The experimentation in England has focused attention on long-term field experiments, and such experiments were soon set up in other lands too. In our days long-term experiments of more than 100 years can be found in six lands. These provide results characteristic first of all for the given site, however they concentrate attention on universally valid, surprisingly actual relations of cause and effect as well. These experiments are of great help to us to reconcile ecological and economic interests and to clear up actual questions of environmentally friendly nutrient supply and sustainable husbandry.

Effect of increasing fertilizer doses on the soluble P, Cd, Pb, and Cr content of soils

Abstract Recently we are witnessing a tremendous pollution of air, water and soil. The environmental pollution is primarily caused by the rapidly increasing industrial production, deposition from gases emitted by road and aerial traffic, utilization of municipal sewage‐water and ‐sludge and other urban and industrial wastes. As for agriculture, fertilization also has an un‐desirable impact on the environment. With the application of phosphorus (P) fertilizers, their heavy metal contaminants, e.g. the very harmful cadmium, may accumulate in the soil. In the National Long‐Term Field Fertilization Trials in Hungary, the effect of increasing fertilizer applications was studied on the plant available, ammonium lactate (AL)‐soluble P and ethylene diamine tetraacetic acid (EDTA)‐soluble cadmium (Cd), lead (Pb) and chromium (Cr) concentration in the upper 20 cm soil layer of three experimental sites. The experiments were set up with two different four‐year crop rotations of winter wheat (Triticum aestivum L.), maize, maize (Zea mays L.) and pea (Pisum sativum L.); winter wheat, maize, maize, winter wheat in nine sites and with a maize monoculture in four sites in 1967–69. The discussed results relate to soil samples taken in the last year of the 7th rotation, i.e. they reflect the long‐term effect of 28 years’ fertilization. Four out of the 40 NPK fertilization treatments were chosen for the present study. There could be detected a marked increase in the available P content in the experimental soils as a result of long‐term fertilization. As compared to the unfertilized control plots, the increase in P content was 2.5–4.6‐fold at the different sites. The environmental impact of Cd, Pb and Cr at the investigated experimental sites was not considerable. Slight concentration increases were detected only for Pb, and the highest Pb contents were measured in the site of heaviest traffic.

Monitoring of gaseous nitrogen losses from nitrogen fertilizers in model experiments

Abstract Gaseous nitrogen (N) losses were studied from N fertilizers applied to winter wheat under field conditions and in large pots in the open section of a greenhouse. The same soil type was used. Ammonium nitrate (NH4NO3), urea [CO(NH2)2], and ammonium sulphate [(NH4)2SO4] distributed at the beginning of tillering were tested in a microplot experiment (16 g N m‐2). Ammonium nitrate applied at different doses in the period between the beginning of tillering and that of flowering was tested in pots filled with 70 kg soil (2 g N pot‐1). The pots were watered. Gas traps of 4.4 dm3 and 1.8 dm3 were laid between the rows of the microplots and into the pots, respectively. Ammonia (NH3), nitric oxide (NO), nitrous oxide (NO2), dinitrogen oxide (N2O), and nitrogen (N2) contents of trapped soil air were analyzed by gas chromatography during vegetation. Nitrogen fertilizer application significantly increased the amount of nitrogenous gases in the trapped soil air and CO(NH2)2application resulted in the highest n...

Correlation between soil K and winter wheat K contents in a network of Hungarian National Long-term Fertilization Trials.

Abstract Tillering stage winter wheat (Triticum aestivum L.) shoot weight, shoot K concentrations, acid ammonium‐acetate EDTA‐soluble (LE‐, Lakanen and Erviö, 1971) and neutral ammonium acetate ‐ exchangeable (Wanasuria et al., 1981) soil K were determined in a network of 28‐year‐old National Long‐term Fertilization Trials (NLFT) with different K fertilization rates at eight experimental sites representing various agro‐ecological and soil conditions of Hungary. Both wheat shoot weights and K concentrations were affected less by K levels than by the different agro‐ecological conditions. The effect of K fertilization, however, was also significant, especially on shoot K contents. The additional effect of a higher K rate, however, was not so substantial. There was no significant correlation between winter wheat shoot K. concentrations and shoot weight. Above 3.0 % shoot K concentrations, however, shoot weights did not increase significantly. Wheat shoot weight increased with increasing soil K values, up to about 150 mg/kg soil‐exchangeable K concentration. Correlation between exhangeable soil K and shoot weight was described by a saturation (Mitscherlich) curve (R=0.6***). Correlation between exchangeable soil K and shoot K contents was also described by a saturation (Mitscherlich) equation (R=0.5***). The lower limit of good K supply, indicated by shoot K concentration at tillering stage (3.0 % K) was usually reached when NH4OAc‐ K reached as high as 150 mg/kg. The closest, linear correlation was found between soil‐exchangeable and LE‐soluble K (r=0.8***). LE extractant dissolved 10% less K than NH4OAc‐ extractant at the average of sites and K levels. Both the LE‐ and the neutral ammonium acetate methods indicated the different soil K levels in a similar way. As a first attempt, new NH4OAc‐ extractable K supply categories were established for the Hungarian agro‐ecolgical conditions, for the non‐ K demanding crop group, including winter wheat. Soil and plant K analyses data proved to be useful tools in adapting the results of long‐term field trials for improved fertilizer recommendations.Tillering stage winter wheat (Triticum aestivum L.) shoot weight, shoot K concentrations, acid ammonium-acetate EDTA-soluble (LE-, Lakanen and Ervio, 1971) and neutral ammonium acetate - exchangeable (Wanasuria et al., 1981) soil K were determined in a network of 28-year-old National Long-term Fertilization Trials (NLFT) with different K fertilization rates at eight experimental sites representing various agro-ecological and soil conditions of Hungary. Both wheat shoot weights and K concentrations were affected less by K levels than by the different agro-ecological conditions. The effect of K fertilization, however, was also significant, especially on shoot K contents. The additional effect of a higher K rate, however, was not so substantial. There was no significant correlation between winter wheat shoot K concentrations and shoot weight. Above 3.0 % shoot K concentrations, however, shoot weights did not increase significantly. Wheat shoot weight increased with increasing soil K values, up to about 150 mg/kg soil-exchangeable K concentration. Correlation between exhangeable soil K and shoot weight was described by a saturation (Mitscherlich) curve (R=0.6 *** ). Correlation between exchangeable soil K and shoot K contents was also described by a saturation (Mitscherlich) equation (R=0.5 *** ). The lower limit of good K supply, indicated by shoot K concentration at tillering stage (3.0 % K) was usually reached when NH 4 OAc- K reached as high as 150 mg/kg. The closest, linear correlation was found between soil-exchangeable and LE-soluble K (r=0.8 *** ). LE extractant dissolved 10% less K than NH 4 OAc- extractant at the average of sites and K levels. Both the LE- and the neutral ammonium acetate methods indicated the different soil K levels in a similar way. As a first attempt, new NH 4 OAc- extractable K supply categories were established for the Hungarian agro-ecolgical conditions, for the non- K demanding crop group, including winter wheat. Soil and plant K analyses data proved to be useful tools in adapting the results of long-term field trials for improved fertilizer recommendations.

Response of two maize hybrids to different fertilizer-N forms (NH4-N and NO3-N)

Abstract It is well‐known that different maize (Zea Mays L.) hybrids can utilize N‐fertilizers to different degrees. Experiments are needed to determine their N utilization manifesting itself in dry weight production and within that in grain weight. The chemical analysis of the plants can give us further information about their quality parameters. Fertilization model experiments were conducted with two maize hybrids (Pioneer 3732 and Volga) of similar yield potential in green house using large pots (40 kg dry clay lessivated brown forest soil per pot) in three experimental years (1993–95). 150 mg N kg‐1 soil was applied in form of NH4NO3 or KNO3. In addition, phosphorus and potassium fertilizers were added too. The plants were grown under two different soil water regimes (65% and 80% water holding capacity) up to full ripening (from May to the middle of September). Compared with the unfertilized control plants, the dry weight of the whole plants and grains in the fertilized treatments was 2–2.5‐fold and 3–4‐fold higher, respectively, on the three years’ average. Volga showed a more favorable response to N‐fertilization, as regards N‐forms, to NO3‐N. The more beneficial effect of N‐fertilization on this hybrid appeared in greater grain yield production, too. The nitrogen harvest index of both hybrids amounted to about 40, 30 and 30% in the KNO3‐, NH4Cl‐ and unfertilized treatments, respectively. The water demand of the hybrids was different, too. Volga produced more dry weight under drier soil conditions. The N‐uptake of both hybrids was considerably higher from the NO3‐N source than from the NH4‐N one, and NO3‐accumulation could be detected in the grains, in ones of Pioneer 3732 to a higher extent. This suggests that nitrate reduction could also take place in the grains. N‐accumulation in the different plant parts was also examined. The yearly variation in the tested parameters was more expressed with the unfertilized plants than with the fertilized ones.It is well-known that different maize (Zea Mays L.) hybrids can utilize N-fertilizers to different degrees. Experiments are needed to determine their N utilization manifesting itself in dry weight production and within that in grain weight. The chemical analysis of the plants can give us further information about their quality parameters. Fertilization model experiments were conducted with two maize hybrids (Pioneer 3732 and Volga) of similar yield potential in green house using large pots (40 kg dry clay lessivated brown forest soil per pot) in three experimental years (1993-95). 150 mg N kg -1 soil was applied in form of NH 4 NO 3 or KNO 3 , In addition, phosphorus and potassium fertilizers were added too. The plants were grown under two different soil water regimes (65% and 80% water holding capacity) up to full ripening (from May to the middle of September). Compared with the unfertilized control plants, the dry weight of the whole plants and grains in the fertilized treatments was 2-2.5-fold and 3-4-fold higher, respectively, on the three years average. Volga showed a more favorable response to N-fertilization, as regards N-forms, to NO 3 -N. The more beneficial effect of N-fertilization on this hybrid appeared in greater grain yield production, too. The nitrogen harvest index of both hybrids amounted to about 40, 30 and 30% in the KNO 3 -, NH 4 Cl- and unfertilized treatments, respectively. The water demand of the hybrids was different, too. Volga produced more dry weight under drier soil conditions. The N-uptake of both hybrids was considerably higher from the NO 3 -N source than from the NH 4 -N one, and NO 3 -accumulation could be detected in the grains, in ones of Pioneer 3732 to a higher extent. This suggests that nitrate reduction could also take place in the grains. N-accumulation in the different plant parts was also examined. The yearly variation in the tested parameters was more expressed with the unfertilized plants than with the fertilized ones.

Applications in sustainable production

Abstract It is well‐known that different maize (Zea Mays L.) hybrids can utilize N‐fertilizers to different degrees. Experiments are needed to determine their N utilization manifesting itself in dry weight production and within that in grain weight. The chemical analysis of the plants can give us further information about their quality parameters. Fertilization model experiments were conducted with two maize hybrids (Pioneer 3732 and Volga) of similar yield potential in green house using large pots (40 kg dry clay lessivated brown forest soil per pot) in three experimental years (1993–95). 150 mg N kg‐1 soil was applied in form of NH4NO3 or KNO3. In addition, phosphorus and potassium fertilizers were added too. The plants were grown under two different soil water regimes (65% and 80% water holding capacity) up to full ripening (from May to the middle of September). Compared with the unfertilized control plants, the dry weight of the whole plants and grains in the fertilized treatments was 2–2.5‐fold and 3–4‐fold higher, respectively, on the three years’ average. Volga showed a more favorable response to N‐fertilization, as regards N‐forms, to NO3‐N. The more beneficial effect of N‐fertilization on this hybrid appeared in greater grain yield production, too. The nitrogen harvest index of both hybrids amounted to about 40, 30 and 30% in the KNO3‐, NH4Cl‐ and unfertilized treatments, respectively. The water demand of the hybrids was different, too. Volga produced more dry weight under drier soil conditions. The N‐uptake of both hybrids was considerably higher from the NO3‐N source than from the NH4‐N one, and NO3‐accumulation could be detected in the grains, in ones of Pioneer 3732 to a higher extent. This suggests that nitrate reduction could also take place in the grains. N‐accumulation in the different plant parts was also examined. The yearly variation in the tested parameters was more expressed with the unfertilized plants than with the fertilized ones.It is well-known that different maize (Zea Mays L.) hybrids can utilize N-fertilizers to different degrees. Experiments are needed to determine their N utilization manifesting itself in dry weight production and within that in grain weight. The chemical analysis of the plants can give us further information about their quality parameters. Fertilization model experiments were conducted with two maize hybrids (Pioneer 3732 and Volga) of similar yield potential in green house using large pots (40 kg dry clay lessivated brown forest soil per pot) in three experimental years (1993-95). 150 mg N kg -1 soil was applied in form of NH 4 NO 3 or KNO 3 , In addition, phosphorus and potassium fertilizers were added too. The plants were grown under two different soil water regimes (65% and 80% water holding capacity) up to full ripening (from May to the middle of September). Compared with the unfertilized control plants, the dry weight of the whole plants and grains in the fertilized treatments was 2-2.5-fold and 3-4-fold higher, respectively, on the three years average. Volga showed a more favorable response to N-fertilization, as regards N-forms, to NO 3 -N. The more beneficial effect of N-fertilization on this hybrid appeared in greater grain yield production, too. The nitrogen harvest index of both hybrids amounted to about 40, 30 and 30% in the KNO 3 -, NH 4 Cl- and unfertilized treatments, respectively. The water demand of the hybrids was different, too. Volga produced more dry weight under drier soil conditions. The N-uptake of both hybrids was considerably higher from the NO 3 -N source than from the NH 4 -N one, and NO 3 -accumulation could be detected in the grains, in ones of Pioneer 3732 to a higher extent. This suggests that nitrate reduction could also take place in the grains. N-accumulation in the different plant parts was also examined. The yearly variation in the tested parameters was more expressed with the unfertilized plants than with the fertilized ones.

Long-term fertilization trials in Hungary

In 1967, according to the proposal of specialists in Hungary, the National Long-Term Fertilization Trials (NLFT) were initiated to establish a uniform network of fertilizer trials representing different agro-ecological regions of the country. The aim of conducting these trials was to study the effects of increasing fertilizer rates on soil nutrients, as well as to predict fertilizer consumption in Hungary. In recent decades environmental pollution in water, soils and the atmosphere has increased; thus investigations on the environmental impact of fertilization (e.g. on soil acidification, nutrient leaching etc.) has become of primary importance. Results obtained in the long-term fertilization trials provide, a) essential information on these processes and b) a reliable database for interpretation of the possible causes of these changes.

Comparison of methods evaluating the plant available potassium content in soils of different types and potassium levels

Abstract The amount and quality of clay minerals in Hungarian soils show considerable differences. In relation to this, in long‐term multi‐location field experiments, different levels of K supply have developed even when fertilized at the same K fertilizer rate. In an incubation experiment (4 weeks at constant temperature and moisture), carried out with the soil samples taken from several sites at these fertilization field trials which were different in their clay content and K levels, changes in the plant available K content in these soils were studied. A high constant dose of K fertilizer was applied on every soil type. Two extraction procedures were used for estimating plant available K content of soils, AL‐soluble (NH4‐lactate, pH 3.7) and NH4‐acetate (pH 7.0), were compared based on the obtained exchangeable amounts of K. As a consequence of the high K dose applied at the beginning of the incubation experiment, plant available K levels measured by the two extraction procedures were significantly diff...

Data presentation, interpretation, and communication

K, Ca and Mg concentrations in tillering stage winter wheat (Triticum aestivum L.) shoot, as well as acidic (pH 4.65) ammonium-acetate + EDTA - soluble (LE-, Lakanen and Ervio, 1971) and neutral ammonium acetate- exchangeable (Wanasuria et al., 1981) soil K, Ca and Mg contents were determined for a network of 28-year-old National Long-term Fertilization Trials (NLFT) with different K fertilization rates at eight experimental sites representing various agro-ecological and soil conditions of Hungary. All the sites had the same fertilization pattern. Correlation between the two soil Ca and the two soil Mg methods, between soil and shoot Ca, and Mg, as well as between shoot K and shoot Ca+Mg contents were evaluated. Close, linear correlations were found between NH 4 OAc-Ca and LE-Ca and between NH 4 OAc-Mg and LE-Mg on non-calcareous soils (r = 0.95). Acidic LE-extractant dissolved significant amounts of Ca and Mg from the Ca- and Mg-carbonates in the calcareous soils. Neutral NH 4 OAc-Ca values increased with increasing soil calcium carbonate contents. Neutral NH 4 OAc-Mg values, however, were the lowest in the calcareous soils, probably due to the large quantities of Ca 2+ more strongly adsorbed to the cation exchange sites of the colloids compared to Mg 2+ . Exchangeable K + values were also small in the calcareous soils, although all of the soils were loams with medium clay contents. There was a positive logarithmic correlation between soil LE-Ca and shoot Ca (R = 0.55), and a quadratic polynomial one between soil LE-Mg and shoot Mg contents, resp. (R = 0.45). The positive logarithmic correlation between NH 4 OAc-Ca and shoot Ca was even closer (R = 0.60). However, there was no correlation between NH 4 OAc-Mg and shoot Mg values. A close negative, logarithmic correlation was found between wheat shoot K contents and Ca + Mg contents (R = 0.78).Abstract K, Ca and Mg concentrations in tillering stage winter wheat (Triticum aestivum L.) shoot, as well as acidic (pH 4.65) ammonium‐acetate + EDTA ‐ soluble (LE‐, Lakanen and Erviö, 1971) and neutral ammonium acetate‐ exchangeable (Wanasuria et al., 1981) soil K, Ca and Mg contents were determined for a network of 28‐year‐old National Long‐term Fertilization Trials (NLFT) with different K fertilization rates at eight experimental sites representing various agro‐ecological and soil conditions of Hungary. All the sites had the same fertilization pattern. Correlation between the two soil Ca and the two soil Mg methods, between soil and shoot Ca, and Mg, as well as between shoot K and shoot Ca+Mg contents were evaluated. Close, linear correlations were found between NH4OAc‐Ca and LE‐Ca and between NH4OAc‐Mg and LE‐Mg on non‐calcareous soils (r = 0.95). Acidic LE‐extractant dissolved significant amounts of Ca and Mg from the Ca‐ and Mg‐carbonates in the calcareous soils. Neutral NH4OAc‐Ca values increased with increasing soil calcium carbonate contents. Neutral NH4OAc‐Mg values, however, were the lowest in the calcareous soils, probably due to the large quantities of Ca2+ more strongly adsorbed to the cation exchange sites of the colloids compared to Mg2+. Exchangeable K+ values were also small in the calcareous soils, although all of the soils were loams with medium clay contents. There was a positive logarithmic correlation between soil LE‐Ca and shoot Ca (R = 0.55), and a quadratic polynomial one between soil LE‐Mg and shoot Mg contents, resp. (R = 0.45). The positive logarithmic correlation between NH4OAc‐Ca and shoot Ca was even closer (R = 0.60). However, there was no correlation between NH4OAc‐Mg and shoot Mg values. A close negative, logarithmic correlation was found between wheat shoot K contents and Ca + Mg contents (R = 0.78).

Studying the effect of organic matter recycling combined with mineral n fertilization in long-term field and model pot experiments: Untersuchung der wirkung der rezyklierung der organischen substanz kombiniert mit mineraldüngung in dauerfeldversuchen und modellgefässversuchen

The effect of various combinations of organic and mineral N fertilizers was studied on the organic matter content of the soil, grain yield, dry matter production and N-uptake of maize. In a model experiment, large pots were filled with 55u2009kg sandy loam soil originating from the plots of the ‘International Long-term Experiments for Investigating the Effect of Organic and Inorganic Fertilisers’ (IOSDV), Keszthely. The field experiment, which was set up in 1983, contained three crop-rotations with maize, winter wheat and winter barley. Treatments: (1) inorganic fertilizers only with increasing N-doses (N); (2) farmyard manuring (FYM) in every third year+N; (3) stalk, straw or green manure+N. Our results clearly proved the advantage of organic matter recycling combined with mineral fertilization over treatment 1. In the fifth and sixth rotations, both types of organic matter recycling resulted in significantly higher Corg contents compared to mineral N fertilization without farmyard manuring or incorporation of crop residues. Grain yields in the field trial were the lowest in treatments without organic matter recycling. In the pot experiment, dry matter production and N accumulation in the grains and vegetative plant parts were also significantly higher in treatments where mineral fertilization was combined with organic matter recycling.