Influence of Soil Fertilization Systems on Chemical Properties of the Soil

OANA-MARIA MUSCALU (PLESCAN), VALENTIN NEDEFF*, ION SANDU, ALEXANDRA DANA CHITIMUS*, ELENA PARTAL, EMILIAN MOSNEGUTU, IOAN GABRIEL SANDU, CLAUDIA TOMOZEI Vasile Alecsandri University of Bacau, Department of Environmental Engineering and Mechanical Engineering, 156 Calea Marasesti Str., 600115 Bacau, Romania Romanian Waters National Administration of Siret Basin, 1 Cuza Voda Str., 600274 Bacau, Romania Gheorghe Ionescu Sisesti, Academy of Agricultural and Forestry Sciences Bucharest, 6 Marasti Blvd., 011464 Bucharest, Romania Alexandru Ioan Cuza University of Iasi, Arheoinvest Interdisciplinary Platform, Scientific Investigation Laboratory, 11 Carol I Blvd., 700506, Iasi, Romania 5 Romanian Inventors Forum, 3 Sf. Petru Movila Str., Bloc L11, III/3, 700089 Iasi, Romania National Agricultural Research and Development Institute, 1 Nicolae Titulescu Str., 915200, Fundulea, Calaraşi, Romania Gheorghe Asachi Technical University of Iasi, Materials Science and Engineering Faculty, 53A D. Mangeron Blvd., 700050, Iasi, Romania

The study has been carried out in the experimental field of National Agricultural Research and Development Institute -Fundulea, Romania, for a wheat monoculture. The researches at INCDA have been carried out following a two-factor experience, stationary and multiannual, mounted in 1968 and up to date, with reference to emphasizing the differentiation of soil's properties as an effect of fertilization sequence, i.e. [12,28,29]: -azote (90 kg·N/ha active matteractive matter); -phosphorous (75 kg·P/ha active matter); -azote and phosphorous (N90P75 kg/ha active matter); -farmyard manure.
Experiments have been carried out for the content of magnesium, aluminium, potassium, calcium, iron and chlorine in the soil. Figure 1 shows soil sampling method used to determine the soil magnesium, aluminium potassium, calcium and iron content [39]. calcium and iron content through atomic absorption spectrometry [39] The metal content in the soil samples has been determined by using atomic absorption spectrometer (AAS), ZEENIT AAS version [39].
The chlorides content in the soil samples has been determined through titrimetric methods [40]: -for the chlorides content we use an aqueous extract, treated according to figure 2.  Results and discussions Table 2 show the experimentally determined values for the soil samples taken on the unfertilized wheat parcel (control sample), for magnesium, aluminium, potassium, calcium, iron and chlorine. The magnesium content (sample from year 2016) value (Fig. 3) registered in the azote fertilized parcel (90 kg·N/ha) was 102.38% higher than the value registered in the unfertilized soil parcel for the 0-15 cm depth, respectively by 107.34% higher than the control sample for the 15-30 cm depth.
For the sample from year 2017, the magnesium content registered in the azote fertilized parcel (90 kg·N/ha) was 8.58% lower than the value registered in the unfertilized soil parcel for the 0-15 cm depth, respectively by 30.19% lower than the control sample for the 15-30 cm depth.
In the case of the phosphorous fertilized parcel (75 kg·P/ha) the soil magnesium content was: -year 2016: 117.46 % higher than the value registered on the unfertilized soil parcel for the 0-15 cm depth, respectively 35.4 % lower for the 15-30 cm depth than the control sample; -year 2017: 122.99 % higher than the value registered on the unfertilized soil parcel for the 0-15 cm depth, respectively 16.2 % lower for the 15-30 cm depth than the control sample.
The magnesium content for the experimental wheat variantsfertilized with azote and phosphorous N90P75 kg/ha (a1b4) and wheatfertilized with farmyard manure (a1b5) was: -wheatfertilization with azote and phosphorous N90P75 kg/ha (a1b4) -year 2016:  For the sample from year 2017, the aluminium content registered in the azote fertilized parcel (90 kg N/ha) was 83.75% lower than the value registered in the unfertilized soil parcel for the 0-15 cm depth, respectively by 89.38% lower than the control sample for the 15-30 cm depth.
For the soil parcel fertilized with 75 kg·P/ha (b3) factor, the aluminium content (sample from 2016) was 78.86% lower than the control sample value, for the 0-15 cm depth, respectively 86.38% lower than the control sample value for the 15 The potassium content (sample from year 2016) value ( Fig. 5) registered for the soil parcel fertilized with azote was 1.59% lower than the value registered for the unfertilized soil parcel for the 0-15cm depth, respectively 5.94% lower than the control sample, for the 15-30 cm depth.
For the sample from year 2017, the potassium content registered in the azote fertilized parcel (90 kg N/ha) was 113.3% higher than the value registered in the unfertilized soil parcel for the 0-15 cm depth, respectively by 13.96% lower than the control sample for the 15-30 cm depth.
In the case of the phosphorous fertilized parcel (75 kg·P/ha) the soil potassium content was: -year 2016: 53.53% lower than the value registered on the unfertilized soil parcel for the 0-15 cm depth, respectively 79.64% lower for the 15-30 cm depth than the control sample; -year 2017: 237.11% higher than the value registered on the unfertilized soil parcel for the 0-15 cm depth, respectively 13.38% lower for the 15-30 cm depth than the control sample.
The potassium content for the experimental wheat variantfertilized with azote and phosphorous N90P75 kg/ha (a1b4) was: -wheatfertilization with azote and phosphorous N90P75 kg/ha (a1b4) -year 2016: • 0-15 cm: 181.86% higher than the valued registered in the soil control sample value; • 15-30 cm: 89.95% of the soil control sample value; -wheatfertilization with azote and phosphorous N90P75 kg/ha (a1b4) -year 2017: • 0-15 cm: 187.12% higher than the valued registered in the soil control sample value; • 15-30 cm: 12.74% lower than the valued registered in the soil control sample value; The potassium content (sample from year 2016) for the experimental wheat variantsfertilized with farmyard manure (b5) was: -0-15 cm: 210.94% higher than the valued registered in the soil control sample value; -15-30 cm: 134.4% higher than the valued registered in the soil control sample value. For the soil parcel fertilized with farmyard manure (b5) the potassium content (sample from year 2017) was 234.46% higher than the control sample value, for the 0-15 cm depth, respectively 12.74 % lower than the control sample, for the 15-30 cm depth.
Calcium content (Fig. 6)   Iron content value (Fig. 7) registered for the soil parcel fertilized with azote (sample from year 2016) was 112.12% higher than the control sample value for the 0-15 cm depth. For the 15-30 cm depth the iron content was 167.15% higher than the control sample value.
For the sample from year 2017, the iron content registered in the azote fertilized parcel (90 kg·N/ha) was 116.49% higher than the value registered in the unfertilized soil parcel for the 0-15 cm depth, respectively by 162.47% higher than the control sample for the 15-30 cm depth.
For the soil parcel fertilized with phosphorous (b3), the iron content (sample from year 2016) was 165.21% higher than the control sample value for the 0-15 cm depth, respectively 114.81% higher than the control sample, for the 15-30 cm depth.
The iron content (sample from year 2017) value (Fig. 7) on phosphorous fertilized parcel was 125.45% higher than the control sample value for the 0-15 cm depth. For the 15-30 cm depth the iron content was 93.14% of the control sample value.
The iron content for the experimental variants wheatfertilization with azote and phosphorous N90P75 kg/ha (a1b4) and wheatfertilization with farmyard manure (a1b5) was: -wheatfertilization with azote and phosphorous -N90P75 kg/ha (a1b4) -year 2016: The chlorine content (Fig. 8) registered for the soil parcel fertilized with azote (sample from year 2016) was (90 kg·N/ha) was 166.66% higher than the value registered for the unfertilized soil parcel for the 0-15 cm depth, respectively 1938.75% higher than the control sample, for the 15-30 cm depth.
For the sample from year 2017, the chlorine content registered in the azote fertilized parcel (90 kg·N/ha) was 60.12% lower than the value registered in the unfertilized soil parcel for the 0-15 cm depth, respectively by 316.67% higher than the control sample for the 15-30 cm depth.
In the case of the phosphorous fertilized parcel (75 kg·P/ha) the soil chlorine content was: -year 2016: 123.77% higher than the value registered on the unfertilized soil parcel for the 0-15 cm depth, respectively 19.11% lower for the 15-30 cm depth than the control sample; -year 2017: 195.63% higher than the value registered on the unfertilized soil parcel for the 0-15 cm depth, respectively 650% higher for the 15-30 cm depth than the control sample. For the soil parcel fertilized with azote and phosphorous (b4), the chlorine content (sample from year 2016) was 112.49% higher than the value registered on the unfertilized soil, for the 0-15 cm depth, respectively 948.75% higher than the value registered on the unfertilized soil, for the 15-30 cm depth.
The chlorine content (sample from year 2017) value (Fig. 8) on phosphorous fertilized parcel was 64.29% lower than the control sample value for the 0-15 cm depth. For the 15-30 cm depth the chlorine content was 225% higher than the control sample value.
The chlorine content for the experimental variant wheatfertilization with farmyard manure (a1b5) was: -wheatfertilization with farmyard manure (a1b5) -year 2016: • 0-15 cm: cu 18.73% lower than the valued registered in the soil sample with no fertilization sequence; • 15-30 cm: cu 870% higher than the valued registered in the soil sample with no fertilization sequence; -wheatfertilization with farmyard manure (a1b5) -year 2017: • 0-15 cm: cu 203.16% higher than the valued registered in the soil sample with no fertilization sequence; • 15-30 cm: cu 239.75% higher than the valued registered in the soil sample with no fertilization sequence.

Conclusions
The research carried out in 2016 and 2017 with regard to the influence of fertilizations systems (fertilization with: nitrogen, phosphorous, nitrogen and phosphorous, farmyard manure) on the chemical properties (magnesium, aluminium, potassium, calcium, iron and chlorine) of the soil emphasized the following aspects: -the magnesium content for the experimental wheat variantsfertilized with azote and phosphorous N90P75 kg/ha (a1b4) was the lower value registered for the level 0-15 cm -44% of the soil control sample value (sample from year 2016); -the magnesium content for the experimental wheat variantsfertilized with phosphorous (75 kg·P/ha) the soil magnesium content was the higher value registered for the level 0-15 cm:122.99% higher than the value registered on the unfertilized soil parcel (sample from year 2017); -in case of aluminium the value registered in the soil, was under soil sample value for the both years (the maximal value registered was for the level 0-15 cm, 26.16% of the soil control sample value -year 2016 and the minimal value registered was for the level 15-30 cm, 6.43% of the soil control sample value -year 2016), for the experimental wheat variantsfertilized with azote and phosphorous N90P75 kg/ha (a1b4); -in case of calcium the value registered in the soil for the level 15-30 cm, was under soil sample value, for all the fertilizations systems applied -the potassium content for the experimental wheat variantsfertilized with phosphorous (75 kg·P/ha) was the lower value registered for the level 15-30 cm, 139.9 mg/kg dry matter (sample from year 2016); -the magnesium content for the experimental wheat variantsfertilized with phosphorous (75 kg·P/ha) the soil magnesium content was the higher value registered for the level 0-15 cm: 1265 mg/kg dry matter (sample from year 2017); -in case of iron the value registered in the soil for the both level analysed, was over soil sample value, for all the fertilizations systems applied making exception the next levels: • 0-15 cm: 64.64% of the soil control sample value (fertilization with azote and phosphorous N90P75 kg/ha, sample from year 2016); • 15-30 cm: 93.14% of the control sample value (fertilization with phosphorous 75 kg·P/ha, sample from year 2017);