Krisztina R. Végh

Effects of nitrogen fertilization on carbon flows in soils with contrasting texture

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

Root and leaf traits, water use and drought tolerance of maize genotypes

The main components of drought tolerance of six maize genotypes were studied to evaluate crop performance in water limiting environments: (1) the postponement of dehydration by reduced transpiration rate (TR) and an increased efficiency of water acquisition from soil; (2) the tolerance of dehydration by effective physiological water use. The aim was to describe the genotype dependent response to drought in leaf and root traits and water relations using data from controlled environment and field experiments, and using dynamic simulation by the Swedish Coup model. High genetic variation was detected in the root density, acquisition efficiency and water use among the genotypes. The female parent lines had the greatest TR with the smallest dry matter accumulation in water deficiency, whereas hybrids could acquire more water from dryer soil while maintaining a lower TR. Hybrid Mv 444 increased water potential more strongly in leaves than hybrid Norma. The postponement of dehydration was observed for Norma, while more tolerance to dehydration characterized Mv 444. Simulation was an effective tool for testing hypotheses considering water acquisition efficiency and for summarizing the results of the measurements in a formalized structure; it helped to quantify the dynamics of water availability and the impact of drought on the growth of the maize genotypes.

Fertilizer effect on Carbon Dynamics of different texture soils under tomato cultures

The risk of nitrate (NO3) leaching is enhanced under tomato culture because of the high water demand, especially in fertilized coarse‐texture soils. To avoid this, slow‐release fertilizers or manure use is recommended. We studied the effect of a slow release and a common fertilizer on the carbon (C) and nitrogen (N) dynamics of drip‐irrigated tomato culture at a macro‐pot (lysimeter) field trial in three different texture soils. The treatments included an initial blanket application of slow‐release fertilizer to all the pots 1 week after planting, followed by supplemental application of N 3 or 6 weeks later. The C and N contents of the microbial biomass differed among the soils. They were significantly less in sandy soil than in the other loam texture soils. A close relation (r2 = 0.85) was found between microbial C and N. Their mean ratio was 6.7, being lowest in the sandy (6.0), and the highest in the clay loam (7.0) soil, but without significant difference. The rate of cellulose decomposition tended to decrease in the sandy soil in each of the three observed periods. The two highest N addition treatments (120 and 180 kg.ha−1 N) accelerated cellulose decay compared with the control and low N addition (60 kg.ha−1 N), especially in the clay loam soil. Nitrate adsorbed by ion‐exchange resin bags in the 0‐ to 30‐cm soil depth did not differ significantly between treatments, and there was no enhancement in nitrate leaching due to repeated fertilizer application.

Nitrogen, phosphorus, potassium, acid, sugar and vitamin C content in tomato grown in different soil types and under different nitrogen doses

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

Barley root growth and phosphorus bioavailability in soil treated with phosphate rocks.

The effects of five phosphate rocks (originating from Algeria, northern Florida, North Carolina, Senegal, and Morocco) with various phosphorus (P) solubilities on P bioavailability, root growth, and P uptake of spring barley crops were studied on an acidic sandy soil in microlysimeters, in a pot experiment and by dynamic simulation. Root length and P influx varied significantly, influenced by the P and calcium carbonate (CaCO3) content and reactivity of the P sources. Phosphate rock (PR) treatments enhanced root growth. The simulation results demonstrated the contribution of root hair formation and P mobilization by rhizosphere acidification in the increased acquisition efficiency of barley in PR‐treated soil.

Simulated and measured nitrogen conditions in tomato culture.

Nitrogen (N) loss by nitrate leaching below the root zone may be great in N‐fertilized and irrigated vegetable soils when root uptake does not deplete the mineral N content of the soil water, which percolates through the soil profile. Soil texture and root growth as well as the dynamics of mineral N concentrations in soil solution are major factors in these processes. Differences of nitrate transport in high productive tomato cultures were studied in different texture soils in an irrigated and fertilized lysimeter experiment. In soil 0–60 cm deep, hydraulic properties were determined and nitrate (NO3)‐N and ammonium (NH4)‐N contents were measured in the beginning and end of the experiment. The soil moisture content was monitored in the 0‐ to 60‐cm soil. Root distribution, the dynamics of shoot biomass, N content, leaf area, and fruit yield were also measured. Interactions of root activity and water and N dynamics were evaluated by fitting the SOIL and SOILN model outputs to measured data. Parameterization of different tomato treatments helps the generalization of experimental findings. Both measurements and simulation results show that N losses via nitrate leaching can be minimized by the use of slow‐release N fertilizer in the establishment period of the crop and by application quick release N fertilizer topdressings after the roots proliferated in the deeper layers. The coupled SOIL and SOILN general models were suitable for the simulation of soil water and N transport and crop growth in the conditions of intensive tomato production.

Sustainability measures of different land use forms in Hungary

We quantified some of the main sources of the SME on farm level for three different plant production forms in Hungary. SME increased in the organic, extensive, intensive farming order from one, two and threefold. However, finding out the most relevant, indicative and locally specific sustainability measures require further studies.

NITROGEN EFFICIENCY IN TOMATO CULTURE

Introduction Vegetable farming has various environmental impacts associated with intensive irrigation and high nutrient use. Sustainability of vegetable cropping systems depends on such a management of the nitrogen flows in crop and soil that prevents nitrate pollution of aquifers while supplying economically reasonable income to the farmers. In 2006 a research project was started aiming the description of the main C and N flows in the soil and crop in vegetable culture, both in terms of the rates of the decomposition of organic matter and the fate of the actual decomposition products. In this paper we focus on the balance between inorganic N input and the N withdrawal of tomato crop in different soil types estimated on the basis of the first year results.

Simulation of carbon flows in crop and soil

SOM (Soil organic matter) is a mixture of living, dead, decomposing organic, and inorganic compounds, derived from plant, animal, and microbial tissue. SOM carbon content reflects a steady state between C accumulation from plant residues and oxidation of the soil organic carbon (SOC) (Toth T. et al. 2003). The level of SOC is determined by a number of interacting factors including precipitation, temperature, soil type, tillage, cropping systems and crop residues. 7 to 80-year intensive cropping and tillage systems may lead to 24-60 % decreases in SOC levels in arable soils in USA and Canada as reported by Smith et al. (1990). Decreasing SOC contents are cause for concern since the organic matter content of agricultural soils is highly correlated with their potential productivity, tilth and fertility. Thus, focusing on protection of soils and their environment, it is essential to understand the dynamics of the turnover of soil organic carbon for the optimization of management practices in crop production.