[en] Nuclear techniques, which include the usage of radioactive and stable isotopes, had been used in soil fertility, plant nutrition, plant breeding, plant protection and food preservation research works after 1950s. Ultimately these nuclear techniques contributed greatly in increased plant production. In general, it is possible to separate the nuclear techniques used in soil fertility and plant nutrition into two groups. The first group is the use of radioactive and stable isotopes as a tracer in order to find out the optimum fertilization rate of plants precisely. The second group is the use of neutron probe in determining the soil moisture at different periods of the growing season and at various soil depths precisely without any difficulty. In research works where conventional techniques are used, it is not possible to identify how much of the nutrient taken up by the plant came from applied fertilizer or soil. However, when tracer techniques are used in research works it is possible to identify precisely which amount of the nutrient taken from fertilizer or from soil. Therefore, the nuclear techniques are very important in finding out which variety of fertilizer and how much of it must be used. The determination of the soil moisture is very important in finding the water needs of the plants for a good growth. Soil moisture contents changes often during the growth period, so it must be determined very frequently in order to determine the amount of irrigation that has to be done. Conventional soil moisture determination (gravimetric method) is very laborious especially when it has to be done frequently. However, by using neutron probe soil moisture determinations can be done very easily any time during the plant growth period. (author)

[en] This study was performed to determine production effectiveness per unit of area from intercropped corn and soybean and to compare their economics with monocropped system taking LER (Land Equivalent Ratio) as a measure of the available yield advantages. Row intercropping experiments design was randomized complete block consisting 3 replicates and 3 N-application methods. In monocropping experiments the same experimental design was also used. In 1983 grain yields od corn when intercropped with soybean ranged from 87 to 89%, in 1984 from 74 to 90% of monocrop. Intercropped soybean yields ranged from 38 to 45% and 64 to 76% of monocrop respectively. Although the yields of component crops in intercropped system were reduced, total yields of the intercrops were greater than that of each crop in monocrop. LERs varied 1.28 to 1.58 and all LERs were 1. This indicated that in intercropping system the land used more efficiently than monocrop. Consequently this system can be economically used in food production in north eastern part of Turkey

[en] A mutation breeding programme for the improvement of yield, oil content and protein content of two soybean varieties was initiated in 1982. In this paper the yields and nitrogen-fixing capacities of several of the resulting mutant lines are reported. The results reveal important genetic variations with regard to nitrogen-fixing ability. 2 refs, 2 tabs

[en] In order to determine the vertical root distributions of Sivas 111/33 and Gerek-79 wheat varieties in the soil profile, two field experiments were conducted at Haymana in 1986, and at Lodumlu in 1987 using tracer techniques and ³²p as a tracer. Randomized complete blocks design as four replications was used. The plot size was 12 m² (240 m by 5.00 m) in which ³²p isotope plots were established with dimensions of 0.07 mxl. 25 m=0.875 m². They included 4 rows of wheat and in the middle of these rows, 15 holes (25 cam apart) were opened with a portable drill. The holes either had depths of 30, 60 or 90 cm depending on the treatment selected. 4 ml carrier-free ³²p solutions were injected into the holes with the help of plastic tubes at two times, one after seedling emergence and the other at early spring. Plant samples for radioactivity measurements were taken at four different growth stages, namely tillering, shooting, heading and full maturity. The results obtained from these investigations clearly showed that: 1. The root growth of plants showed differences depending on growth stage and variety. 2. At tillering stage the roots of both wheat varieties were not able to reach to the 90 cm soil depth, however, Sivas 111/33 had relatively shallow rotting system and Gerek-79 had deep rooting system at this stage. 3. At shooting, heading and full maturity stages Sivas 111/33 had more roots than Gerek-79, while at 30 and especially 60 cm soil depths Gerek-79 had more roots. Nearly 26%, 32% and 42% of the total roots of Sivas 111/33, and 15%, 42% and 43% of the total roots of Gerek-79 were found at 90, 60 and 30 cm soil depths, respectively. 4. When compared with Gerek-79, Sivas 111/33 was found to be more suitable for drought conditions

[en] This investigation was carried out to determine the relationships between fertilizer N leaching and N fertilizer application time, method and irrigation rate by using ¹⁵N methodology. Therefore, in the field experiments, the effects of three factors namely a) Irrigation rate (optimum 240 mm, high 360 mm), b) N application time (All at planting, 1/2 at planting and 1/2 after planting when plant heights were 50 cm), c) N application method (side dress and broadcast) were investigated. The field experiments were conducted using randomized block design as split-split plot and 4 replications. As the test plant hybrid corn was selected and at planting row spaces were arranged as 0.80 m x 0.25 m. Nitrogen was applied 120 kg N/ha to the all treatments as urea fertilizer (46 % N). In addition, to the sub-plots (which received half of N at planting and the other half when plant heights were 50 cm) ¹⁵N labelled urea (2.63 % ¹⁵N a.e. as 120 kg N/ha) was applied. After harvesting, total N and ¹⁵N analyses were done for plant and soil samples. The results showed that the seed and total yields were increased with higher (360 mm) irrigation. When N application was side dressed the availability of N was increased, and also its loss by leaching from the active root zone was decreased. In conclusion, it was observed that at high irrigation rate was saved about 84 kg N/ha by side dressing rather than broadcasting of the applied N fertilizer

[en] Nuclear techniques that are in use in agricultural research in Turkey are : a.) techniques for monitoring and assessing the environmental pollution - such as monitoring the pesticides residues in food and soil using¹⁴C labelled pesticide's ; also plant root investigations using ³²P; b.) techniques for reducing the impact of increased plant productivity - such as the use of N tagged chemicals for optimizing the N fertilizer use and to determine the N₂ - fixation capacities of legumes. Also improving the water management practices - such as the determination of soil water , soil moisture characteristic cures and the leaching in soils by using the neutron probe; c.) techniques for agricultural resource development - such as the use of ⁶⁰Co and ¹³⁷Cs for obtaining new genotypes. The benefits and disadvantages of the application of nuclear techniques in agricultural research will be reviewed

[en] In order to determine the N₂-fixing capabilities of several soybean mutant lines under different N rates and inoculant types, two different field experiments were conducted at Antalya and Adana in 1989. In experiment I mutant soybean lines C_k, C₂, C_g, A_k, A₈, A₉ were investigated at 15 and 30 kg N/ha rates of ammonium sulphate (21 %N), where all seeds were inoculated with ''Azotek'' inoculant. In a second experiment, experiment II same mutant lines were investigated using two inoculant - (Entite and Azotek) where 15 kg Na/ha ammonium sulphate (21 %N) was applied. As reference crop, corn was used in all experiments. ¹⁵N isotope plot with dimensions of 1.0mx1.5m=1.5m² were established in each plot. 2.5% ¹⁵N atom excess for low N rates and 2.0% ¹⁵N atom excess for low N rates and 2.0% ¹⁵N atom excess for high N rates were sprayed to the ¹⁵N isotope plots as 250 ml aqueous solution just after sowing at both locations. At maturity all plants were harvested at the same time. Total N analysis in ground plant samples were done by micro-Kjeldahl procedure and ¹⁵N determinations were made by emission spectrometer. Results showed that increasing the N rate increased the %N dff, %Ndfa and total N fixed by the soybean mutant lines. Also %Ndfa and total N₂ fixed varied between the soybean mutant lines according to the inoculant type, the mutant line C-9 had the highest %Ndfa and total fixed N values, among others

[en] In order to find suitable varieties of tomato, pepper and cucumber for plastic greenhouse conditions in Ankara and eventually to identify the best N fertilizer rate greenhouse experiments were conducted for two years. Yazgi F₁ variety for tomato, Hizir F₁ variety for cucumber and Serademre 8 variety for pepper were chosen to be the suitable varieties to grow in the plastic greenhouse conditions in Ankara. Five N treatments [N₀=0, N₁=150, N₂=300, and N₃=450 kg/ha; also, soil N application treatment (N_soil) equivalent to the fertigation treatment of 300 kg/ha was included for tomato and pepper, however N rates for cucumber was 131, 266 and 339 kg N/ha; N_soil being 266 kg N/ha] were investigated using ¹⁵N labeled urea fertilizer. Significantly higher marketable fresh fruit and total dry matter yields and N uptakes values were obtained from N₃ treatments for tomato and cucumber, but from N₂ treatment for pepper. Also, significantly higher yields, N uptakes and % NUE values were obtained when the same amount of N fertilizer is applied through fertigation compared to the treatment where N fertilizer applied to the soil then drip irrigated. (author)

[en] The measurement of biological N₂ fixation is of considerable importance and recently ^AN values of the legume and non-nodulating crop using 1^5N labelled fertilizer were used extensively to estimate the amount of N₂ fixed legume crop growing under field conditions. The objective of this research was to estimate biological N₂ fixation under field conditions using 1^5N labelled fertilizer and growing Calland soybean and corn as the test plants. A field experiment was conducted at Cukurova (Adana) using randomized block design and 4 replications for each treatment. For the both crops 4 nitrogen rates and for soybean 4 inoculation rates were applied. (author)

[en] Nine field experiments were conducted on potato yield, N uptake , N fertilizer residue in the soil end the portion of N fertilizer leached below 200 cm of soil depth in the Cappadocia region of Turkey. The N rates used in these experiments were 0, 200, 400, 600, 800 and 1000 kg N/ha with a completely randomized block design with 3 replications. Nitrogen fertilizer was applied in two equal portions; one at planting and one just before the first irrigation. Although all yield data were used to find out the marketable tuber yield - the N rate response curve and the fate of applied fertilizer N was determined only for the 400 and 1000 kg N/ha rates. Isotope micro plots were established where ¹⁵N-labelled ammonium sulphate was applied at % 5.0 and 2.5 atom excess enrichments for 400 and 1000 kg N/ha rates, respectively. At harvest, marketable and dry tuber yield was determined for all N rates. Dry tuber and leaf plus vine yields were determined for the isotope micro plots and they were analyzed for the % N and % ¹⁵N atom excess. The percent N derived from fertilizer ( % Ndf f ) and N use efficiency ( % NUE ) were calculated for the plant samples. The ¹⁵N-labelled residue left in 0- 200 cm soil was also determined. The amount of N fertilizer leached beyond 200 cm soil depth was also calculated. ¹⁵N-labelled nitrate and total nitrate of the groundwaters from wells were determined at different dates. The results show that the optimum marketable tuber yield was obtained with 600 kg N/ha. Tuber N uptake was increased slightly, while leaf plus vine N uptakes increased considerably as the N rate was increased from 400 to 1000 kg N/ha. The percent NUE values decreased nearly by half and the amount of N fertilizer in the 0- 200 cm soil layer increased more than 3 times when the N rate was increased from 400 to 1000 kg N/ha. Nearly half of the applied fertilizer N (45.6 % ) at 400 kg N/ha and more than half of the applied fertilizer N (60.8 % ) at 1000 kg N/ha was still in 0 - 200 cm soil depth after harvest. Four times more N fertilizer was leached beyond 200 cm soil depth when 1000 kg N/ha nitrogen was applied in stead of 400 kg N/ha rate. The results also indicate that the potential of contamination of the groundwaters do exist due to leaching of the applied N fertilizer. (Au)