THE INFLUENCE OF NITROGEN, PHOSPHORUS, AND POTASSIUM FERTILIZERS ON SPRING BARLEY PRODUCTION AND HARVEST INCREASE

: The study was conducted in the experiments with long-term fertilizers in non-irrigation conditions in 2016 and 2021. The experiments were based on the two-factor subdivision method. Factor A doses of Nitrogen and Phosphorus N 0 P 0 , N 60 P 40 , N 60 P 80 and N 120 P 80 respectively factor B Potassium doses K 0 , K 40 , K 80 and K 120 . Fertilizers were applied in the fall under the plow and in the spring. The average monthly temperature was higher in April, June and July for 2016 and June and July in 2021, compared to the 65-year average. The average values of monthly precipitation were higher in 2016 during the vegetation period

the level of the whole plant (Naseem et al. 2014;Pettigrew, 2008). Potassium is the "third element in fertilization" or even the "forgotten element" (Kraus, 1997 quoted by Rusu, 2021). The level of approach and application of K occurs after the application of nitrogen and phosphorus (N, P) Potassium plays an important role in determining the improved resistance of K-adequate plants to diseases (Leathand Ratcliffe 1974; Trolldenier 1982; Perrenoud 1990 quoted by Brennan et al, 2007).
The analysis of the efficiency of potassium application has as its essential purpose a control and obviously a monitoring of its presence, with the achievement of essential roles in its circuit in the soil-plant system. The specific management of this fertilizing element it is dependent on the essential characteristics of the soil and nutrition, in relation to this nutrient (Borlan et al, 1994).
The above assessments are relevant, in general, in the context of the exclusive application of mineral NPK but principled observations regarding organic and organo-mineral resources are also valid and their functionality in the context of the determining factors in the NPK effect.
For the fertilization of the spring barley crop, it is observed if the destination of the harvest is use for the production of beer, smaller amounts of fertilizers will be applied for a crop with a lower protein content, instead if the purpose of the harvest is for animal feed then the doses can increase up to the limit of the resistance of the cultivated variety to fall.

MATERIAL AND METHOD
The study was conducted within the experiments with long-term fertilizers in non-irrigated conditions in 2016 and 2021. The experiments were executed according to the method of subdivided plots with two factors: factor A doses of nitrogen and phosphorus N0P0, N60P40, N60P80 and N120P80 respectively factor B doses of Potassium K0, K40, K80 and K120. Phosphorous and potassium fertilizers were applied in the fall under plowing and in the spring those with nitrogen. The cultivated spring barley variety was Romaniţa, a creation of ARDS Turda.
In the NPK experiments with long-term fertilizers from Turda, the following crops are studied: winter wheat -corn -winter wheat -spring barley -soybeans, thus each crop returns to rotation after a 5-year cycle. For this reason, are presented the data obtained for the spring barley crop from the years 2016 and 2021.
The results were statistically processed by the variance analysis method and the lowest significant difference was determined -DL -(5%, 1% and 0.1%). Also, the interaction between factors is presented and the increase in production per 1 kg of active substance applied (ANOVA, 2015).
The soil type is defined as cambic para rendzina epicalcare clayey chernozem (SRTS 2012; 2012+), which may have similarities with para rendzina cambic chernozem (after SRTS 1980). The pH is within the limits of neutral -weakly alkaline, high humus content, the regime of phosphorus in its mobile forms, it appears with reduced values in the deep horizons and average in the surface ones and the soil supply with potassium is good (Ceclan, et al, 2022).
The different climatic situation of the two experimental years shows a significant effect of the rainfall regime during the vegetation period of the spring barley crop in favoring the effect of the applied fertilizers and the valorization of the essential NPK interaction. From a climatic point of view for the year 2016 it is estimated that the average temperatures were higher in the months of April, June, July and the highest in July 2021, compared to the 65-year average (table 1). Average monthly precipitation values were higher in 2016 for the entire growing season and in 2021, for the months of May and July they were above the average of 65 years (table 2). Thus, in the two studied years, nitrogen and phosphorus differentiated higher productions in 2016 when the level of precipitation was higher and lower in 2021 when there was a low level of precipitation in June. Based on these results, it can be concluded that the spring barley which consumes the necessary nutrients until the grain filling phase that the high temperatures but especially the lack of water in the soil favor the influence of potassium for the year 2021 compared to 2016. The interaction of NP and K mineral fertilizers offers better results in 2016 characterized as a rainy compared to the year 2021 in which April was a little dry and June very dry. From the values of the F sample is presented, the decisive influence of NP fertilization followed by the K effect and the NP x K interaction in determining grain production in spring barley crop (table 3). Fertilizers have a decisive role in the realization of productions, therefore, depending on the applied dose, they act differently. For the two years studied 2016 and 2021 (table 4) the influence of potassium fertilizers causes differences to the dose N0P0K0 very significantly superior to the dose N0P0K120 of 314 kg/ha in 2016 and distinctly significantly superior to the dose N0P0K40 with a difference of 373 kg/ha, respectively very significantly superior to the doses N0P0K80, with 513 kg/ha and N0P0K120 with 814 kg/ha in 2021. For the doses N60P40 in 2016 the differences were ensured statistically very significantly superior with 412 kg/ha at K40, 327 kg/ha at K80, and 836 kg/ha at K120 to N60P40K0. In 2021, the harvest increases for doses K80 (641 kg/ha), K120 (451 kg/ha) there were registered statistically very significantly higher differences compared to N60P40K0.
Potassium efficiency could be defined as the ability of a species or cultivar to produce a high yield in a soil limiting in K for a standard species or cultivar (El Dessougi et al, 2002) If the doses of potassium applied on a background of NP are increased yield increases due to potassium may have reductions in the year 2016 primarily as an effect of induced nutritional imbalances or excessive doses of K. Instead in the year 2021, considered as normal climatic, the doses applied with this element they ensured significant production differences, but all results are based on NP fertilization as a background that ensures the potentiation of the K effects or clearly the interaction NxPxK.
Some studies presented that plant species and even cultivars within a species differ in their K efficiency (Zhang et al, 1999;Fageria et al, 2001). Plants may differ in their K efficiency due to differences in acquisition ability by the roots or utilization by the plant or both (Marschner, 1995). Utilization efficiency is defined as dry matter production per unit K in the dry matter. Acquisition efficiency is defined in terms of total uptake per plant or specific uptake per unit root length (Marschner, 1995).
Thus, in 2016 significantly lower differences were recorded -262 kg/ha for K80 to N60P80K0, and in 2021 the differences recorded at K120 (315 kg/ha) were provided statistically significantly superior to N60P80K0. For doses of K40 the differences were ensured statistically very significantly superior with 576 kg/ha in 2016 and 468 kg/ha in 2021 to N120P80K0. At the maximum dose applied K120 difference of -451 kg/ha was significantly lower in the year 2016 and distinctly superior with 351 kg/ha in 2021 to N120P80K0 (table 4). In the two studied years in all cases the differences in production were ensured statistically very significantly superior to the control, the highest productions were obtained at the doses N120P80K40 5866 kg/ha followed by N120P80K80 5344 kg/ha, N120P80K0 5291 kg/ha and N60P80K0 5291 kg/ha in 2016 and in 2021 N120P80K40 (5719 kg/ha), N120P80K120 (5601 kg/ha), N120P80K0 (5251 kg/ha) and N120P80K80 (5153 kg/ha). The essential regularity deduced here is that the production differences due to the application of potassium in this experimental setting, are reduced and take into account that in most significant situations the application of this element highlights the function of regulating the effects of nitrogen (situations present especially on the background of NP where nitrogen has the maximum presence of N120 per unit area). In the rest of the alternatives, potassium application is at similar levels to NP (N60P40; N60P80). Thus, the highest productions follow the presence, almost entirely, of the maximum dose of N (N120), which is first supported by the presence of phosphorus (especially level P80) then potassium applied even modestly (40 -80) which regulates and shapes an adequate fertilization system for spring barley.
It is well known that nitrogen significantly influences plant growth and development. Knowledge of the physiological mechanisms that contribute to the absorption and use of nitrogen are particularly important to increase the efficiency of the use of this chemical element (Alina Laura AGAPIE, et al 2021).
In order to finalize a rational management of fertilization in spring barley, the use of this system as a basis, the application and capitalization of NP interaction, is justified first of all before or simultaneously with sowing which materializes with primary and priority effect in all the tested variants which proves that the two elements in complementarity with plastic roles, constitutive and quantitative give the size level of the grain harvest. (table 5). From the experimental data and the production results, in general, in a spring barley fertilization management, effective doses at N -60 and below N -120 can be noted; at P -40 -80 and for K -40 -80, so with the mention of a balance and ratio N:P:K of 1:1:1. The effects of excess N in vegetation and quality are thus avoided, a control of the essential nitrogen regime and, last but not least, high grain production, based on distinct effects.