Einfluß der Stickstoffdüngung auf Ertrag,Ertragsstruktur und N-Verwertung von Winterweizen - Möglichkeiten und Grenzen der Bestandesführung

Influence of nitrogen level on yield, yield structure and N utilization of winter wheat - Possibilities and limits of crop management In pot experiments the influence of number of plants per pot (10 or 20), nitrogen level (1,2 - 2,4 - 3,6 g N/pot) and application date (DC 21-29-32/37-51) on yield components, grain yield and nitrogen uptake was investigated. Number of stalks per plant were influenced by removing all tillers except one or two compared to untreated. In pots with 10 and 20 plants, yield was uneffected by the number of tillers removed. Similarly, small differences were observed in the number of earbearing stalks, grain per ear and weight of 1000 seeds. Yield components were not influenced by N-application at 2,4 g N/pot. Removal of tillers to one or two per plant resulted in high 1000 seed weight (58 g) and great number of seeds per ear (55) but not in high yields. The importance of a compensatory relation between the number of earbearing shoots, number of seeds per ear and 1000 seed weight for yield formation and N uptake is discussed.     

Einfluß der NO3- bzw. NH4-Ernährung auf Ertrag und Nitratgehalt von Spinat und Kopfsalat

Influence of NO₃ and NH₄-nutrition on yield and nitrate content of spinach and lettuce Field and pot experiments were conducted in order to study the effect of N-supply (N_min + N-fertilization) and partial and complete NH₄-nutrition on yield and nitrate content of spinach and lettuce. The highest yields were obtained when the N-supply of spring spinach was 250 kg N/ha, autumn spinach 200 kg N/ha and lettuce 120 kg N/ha. Nitrate content of plants could be diminished by reducing N-supply. However, if N-supply is below the optimum value yield depressions are inevitable. NH₄-nutrition reduced in both species nitrate content. But, spinach yield was reduced heavily. Very low nitrate content of plants occured, when N-nutrition of plants cultivated in nutrient solution, was changed from NO₃ to NH₄ during the last days before harvest. Herewith similar weights and head quality were obtained as with permanent NO₃-nutrition.     

Quantitative Mineralbestimmung in der Schlufffraktion von Böden auf der Grundlage der chemischen Analyse und unter Anwendung der Karl-Fischer-Titration. II. Ergebnisse bei Böden aus Geschiebedecksand,Geschiebemergel und Löß

Quantitative estimation of the mineralogical composition from silt-fractions of soils on the basis of the chemical analysis and by application of the Karl-Fischer-titration. II. Results obtained with soils from glacial sand, boulder marl and loess The contents of micas and feldspars were quantified in the silt-fractions from horizons of a podsolic brown earth developed on glacial sand and of lessives on loess as well as on boulder marl by using a method that has been described in detail in part I. Three components each of micas and of feldspars, namely muscovite (Ms), phlogopite (Phl), annite (Ann), orthoclase (Or), albite (Ab) and anorthite (An) were determined. The silt fractions of the three investigated soils are similar in their mineralogical composition. Feldspars are composed of equally high amounts of Or and Ab. Micas are dominated by the Ms-component. Apparently the mica content of the silt fractions is reduced during soil development, whereas no significant changes can be found for feldspars. The loss of micas is responsible for the decreasing potassium content of the silt fractions.     

EDV-gestütztes Meß- und Auswerteverfahren zur Bestimmung der ungesättigten Wasserleitfähigkeit nach der Verdunstungsmethode

A Computer-aided Measuring and Evaluation Method for the Determination of the Hydraulic Conductivity in the Unsaturated State according to the Evaporation Method Multiple methods for the determination of the unsaturated flow depend on the water content or the soil-moisture tension have been published by so far. Their major drawback is the large consumption of time for the measuring and/or for the evaluation. The here presented combination of devices for the application of the evaporation method including its software permit a faster determination of parameters and a presentation in an analytic mode.     

Pflanzenverfügbarkeit der Phosphatvorräte ackerbaulich genutzter Böden. -Langfristige Feldversuche zur Nutzbarkeit des Bodenphosphors und zur Bewertung der Bodenuntersuchung -

Availability of Phosphate Reserves in Arable Soils - Long Term Field Experiments for Assessing Soil P Reserves and Critical Soil Test Values - The objective of this work is to quantify the plant availability of soil P reserves accumulated by former fertilizer applications, the possibility of utilizing them by arable field crops and to determine critical soil test values. For this purpose several long term field experiments with large plots without replicates were initiated in 1977 on luvisols from loess (pH 6.8 – 7.4) in Lower Saxony with a sugar beet - winter wheat - winter barley/winter wheat crop rotation. Annual P applications were 0, 45, 90, 135 and 180 kg P₂O₅/ha as triple phosphate. Application of other fertilizers and plot management were according to farmer's practice. Despite of high yield levels phosphate response of plants was only 2 % at its maximum in the average of all crops in 15 years. This was confirmed by small plot experiments with four replicates placed into the large plots after 9 years, when soil P levels had been differentiated under the influence of plant P removal and P application. Herewith in agreement, shoot P concentration was found within the range generally regarded sufficient. It is therefore concluded that plant P demand has been fully satisfied by soil P reserves. Soil P test values, monitored by the P(H₂O) method of Sissingh, decreased markedly in 15 years, when no P was applied, they remained approximately constant when P application was equal to P removal and they increased when P addition was higher than P removal. Plants on a site with 4 mg P(H₂O)/L initially had severe P deficiency. Maximum yield was obtained when the soil P level was raised to 11 mg P(H₂O)/L. It is concluded that P reserves, which are often high in German arable soils, can be utilized by field crops and thus be lowered to about 10 mg P(H₂O)/L by reducing or omitting P dressings. For practical purposes it is suggested to restrict P application, if necessary at all, to the sugar beet crop in the rotation because they often respond more than small grain.     

Morphologie und Alter von Böden der Südlichen Frankenalb und der nichtkarbonatische Mineralbestand der Kalksteine

Morphology and age of soils in the ‘Südliche Frankenalb’ and the noncarbonate mineral composition of the limestones Soils in the ‘Südliche Frankenalb’ are described according to their local particle size and color characteristics, and their typical situation in the landscape. ‘Solifluction’ (mixing of limestone fragments with terra fusca solum) and sedimentation of aeolian material were the important processes which complicate the reconstruction of soil formation. The quantities of carbonate-free residues of limestones vary in a wide range between 0.7 and 25.4%. With this property, a grain size- and a mineralogical property, the limestone samples are separated by discriminant analysis in three groups. In contrast, the clay mineral composition of all the limestone residues is very homogeneous. In the fine clay fraction (< 0.2 μm) and coarse clay fraction (2-0.2 μm) illite and illite/smectite mixed layer minerals are the predominant minerals with proportions of 90% and 80–85%, respectively. The time necessary for soil formation is calculated to be 1.6 (20 cm depth, IIT-horizon) and 2.7 million years (36 cm depth, IIT + Bv₂-horizon), respectively. This calculation is based on a Malm Delta limestone (0.7% residue). The carbonate output is calculated from CaCO₃ solution rates in the CO₂-H₂O system and actual leaching rates derived from local climate data. The period of soil formation from other limestones was not as long.