Investigations on the change of soil chemical and biological characteristics as influenced by crop rotation and long-term fertilization in the Moldavian Plain

Investigations conducted in long-term (39 years) stationary experiments, under non-irrigated, followed the influence of different fertilizer rates on the evolution of soil agrochemical characteristics and yield obtained in main crops, placed in 2, 3 and 4 year rotations. In maize crop, placed in 5 year rotations, the mean yield obtained during 1980-2005 was of 5920 kg /ha. Rates of N100P100 have determined yield increases by 94% (3030 kg/ha) and rates of N40P40 + 30 t/ha manure resulted in a double yield, in hybrid Oana (9 %; 3180 kg/ha) compared to unfertilized. The long-term use of 3 and 4 year rotation with ameliorative plants resulted in getting yield increases by 46 - 48% (1120-1150 kg/ha) in wheat and 27 - 35% (1180 – 1530) in maize, compared to continuous crop. Annual application of rates of 80 kg/ha P2O5 determined the accumulation of a reserve of mobile phosphates in soil, comprised, according to applied nitrogen, between 47 and 66 ppm. The humus and nutrient content from soil was maintained at a supply level proper to the requirements of plant nutrition, only under 3 or 4 year rotation and in case of annual use of rates of at least N100P100 or of mean rates of mineral elements with 30 t/ha manure

Investigations on the influence of fertilization system and erosion on wheat yield and on some soil agrochemical characteristics

By diminishing soil fertility, the erosion process determined the differentiation of mean wheat yield according to slope and erosion, from 3905 (100%) to 3078 kg/ha (78.8%). The mean annual losses of yield registered in wheat in the last 10 years, caused by erosion, were of 827 kg/ha (21.2%). The humus and nutrient content from soil was maintained at a supply level proper to the requirements of plant nutrition, only under 3 or 4 year rotation, and in case of annual use of rates of at least 100 kg N + 100 kg P2O5 or mean rates of mineral elements with 60 t/ha manure. The use of mineral fertilizers with manure resulted in increasing mobile phosphorus content from soil until 94 ppm, achieving a good and very good supply in mobile phosphorus and increasing humus content from soil to 4.18%. On weakly and highly eroded soils, the application of moderate rates of mineral fertilizers with 3 t/ha pea stalks determined the improvement in soil ureasic and phosphatasic potential, ensuring a better plant supply with assimilate phosphorus. The use of manure or residues, which are easily degradable with mean rates of mineral elements, resulted in achieving soil nutrient supply and biological characteristics very close to those obtained by using high rates of mineral fertilizers. On slope lands, poor in organic matter and mineral elements, establishing the best fertilizer rates, which ensure crop consumption and maintain good soil supply in mineral elements, is more difficult, especially in crops requiring high amounts of mineral elements, as wheat and maize

Influence of crop rotation and long-term fertilization on wheat and maize yield and soil fertility in the Moldavian Plain

Investigations, set up in 1968, were carried out on a Cambic Chernozem with a slope of 14%. They have shown the influence of different crop rotations and fertilization on soil erosion and fertility. The mean yield increases in wheat, during 1980-2007, were between 23 and 26 % (646 – 736 kg ha−1), due to crop rotation and between 57 and 101 % (1099 – 1949 kg ha−1), due to applied fertilizer rates. On slope lands from the Moldavian Plain, a good supply in mobile phosphorus for field crops (37-72 mg kg−1) was kept in case of the annual application of a rate of N100P80, and a very good supply in mobile phosphorus (69-78 mg kg −1) and mobile potassium (over 200 mg kg−1) was found at a rate of N60P40+30 t ha−1 of organic manure, applied in 3 or 4 -year crop rotations with legumes and perennial grasses. The total carbon mass on Cambic Chernozem from the Moldavian Plain has registered significant increases at higher than N140P100 rates, at organo-mineral fertilization and in 4-year crop rotation + reserve field cultivated with perennial grasses and legumes. In maize continuous cropping and wheat-maize rotation, very significant values of the carbon content were found only in organo-mineral fertilization, in 4-year crop rotation + reserve field cultivated with perennial grasses and legumes, and at N140P100 fertilization. The mean annual losses of nitrogen, phosphorus and potassium, once with water runoff and eroded soil on 14% slope fields were of 19.9 kg ha−1 in maize continuous cropping, 11.9 kg ha−1 in wheat-maize rotation and 8.1 kg ha−1 in rotation peas-wheat-maize-sunflower + two reserve fields cultivated with perennial grasses and legumes

Investigations on the influence of longterm fertilization on wheat and sunflower yield and soil fertility in the Moldavian Plain

The investigations conducted in stationary experiments, at the Podu-Iloaiei Agricultural Research Station, which were set up in 1967, under nonirrigated, have followed the influence of mineral fertilization on wheat and sunflower yield and on the evolution of soil physical, chemical and biological characteristics. In bean-wheat-sunflower-wheat-maize crop rotation, applying mineral fertilizers during 2005-2008 has resulted in getting mean yield increases, which varied, according to rates, between 41 and 94% (767-178 kg/ha) in sunflower (N40P40-N120P80) and between 89 and 146% (1658-2718 kg/ha) in wheat (N80P80-N160P80). The mean yield increases, obtained for each kg of a.i. of applied fertilizer, were comprised between 8.4 and 8.9 kg in sunflower (N80P80-N120P80) and between 11.3 and 16.2 kg in wheat (N60P40- N160P80). On the Cambic Chernozem from the Moldavian Plain, a good supply in mobile phosphorus in bean-wheatsunflower- wheat-maize crop rotation (47 mg/kg) was done at the annual application of a rate of N80P40, while a very good supply (93 mg/kg) was achieved at the rate of N160P100. After 41 years of experiences, in bean-wheat-sunflower-wheat-maize crop rotation, the content of organic carbon from soil has decreased by 22.5% (4.5 g/kg soil) at the unfertilized control, by 17.0% (3.4 g/kg soil) at the rate of N80P80 and by 13.5% (2.7 g/kg soil) at the rate of N120P80. After 41 years of experiences, in bean-wheatsunflower- wheat-maize crop rotation, with high fertilizer rates (N160P80), the content of organic carbon from soil had close values to the initial ones, with a slight diminution of approximate 0.31 g / kg soil/ year

Influence of organo-mineral fertilization on wheat and maize crops and the evolution of soil fertility under long-term experiments in the Moldavian Plain

The investigations conducted during 1996-2007 at the Podu-Iloaiei Agricultural Research Station have studied the influence of different organo-mineral fertilization rates on wheat and maize yield and soil agrochemical characteristics. In wheatmaize crop rotation, applying mineral fertilizers has resulted in getting mean yield increases. The organic fertilizers, applied together with mineral ones (N50P50+60 t manure/ha), have improved soil chemical characteristics and determined mean yield increases of 125% in wheat and 108% in maize. The mean yield increases, obtained for each kg of a.i. of applied fertilizer, were comprised between 7.6 and 17.5 kg in wheat and between 13.0 and 28.1 kg in maize. In the intensive rotations with cereals, with high annual consumption of nutrients, maintaining a good soil supply with humus and mineral elements was done only by the organo-mineral fertilization (N50P50 or N100P100 + 40 t manure/ha). In the soils from the Moldavian Plateau, which are poor in organic matter and nutrients, the proper use of different organic resources may replace a part of high technological consumption, determined the improvement in the content of organic matter from soil and ensured better conditions for the capitalization of nitrogen fertilizers. On the Cambic Chernozem from the Moldavian Plateau, a good supply with mobile phosphorus in wheat and maize crops (37-72 mg/kg) was done in case of the annual application of a rate of N100P100, while a very good supply (72-91 mg/kg) was achieved at the rate of N50P50+60 t/ha manure

The influence of fertilization and erosion on maize crop, grown on eroded soil, and on soil agrochemical and biological characteristics

Investigations conducted during 1997 - 2006 on a cambic chernozem at the Agricultural Research and Development Station of Podu – Iloaiei have studied the influence of different fertilizer systems on yield in wheat and maize crops, and placed in a three-year rotation (pea – wheat – maize). The erosion process has determined the differentiation of average maize yield, according to slope and erosion. The mean annual losses of yield registered in wheat in the last 10 years, caused by erosion, were of 1296 kg/ha (22.1%). On weakly eroded lands, mean maize yields obtained during 1997-2006, were comprised between 3227 kg/ha at the unfertilized control, and 7678 kg/ha at rates of N70P70+ 60 t/ha manure. On highly eroded lands, the mean yield obtained under unfertilized was of 2346 kg/ha. Average yield increases obtained by applying 60 t/ha manure, every two years, were of 41.3 kg grains per t of manure applied. Mineral fertilizers (N100P100) resulted in obtaining mean yield increases of 13.6 kg grains/kg a.i. of applied fertilizer. On slightly eroded lands, maintaining a good supply level in soil nutritive elements was done by the annual use of fertilizer rates of at least N100P100 or N70P70+ 40 t/ha manure, applied once in two years, or N70P70 + 6 t/ha straw. On highly eroded lands, maintaining a good plant supply in mineral elements was done at rates of N140 P100K70 or N70P70 + 40 t/ha manure. The total number of microarthropods from soil, at the depth of 0-30 cm had values between 22.4 samples/100 cm2 in the fertilized plot with N70P70 + 6 t/ha straw, and 78.5 samples/cm2 in the fertilized plot with N70P70+40 t/ha manure. In most of the fertilization variants, the highest values were registered in Collembole. In case of manure fertilization and on the plot cultivated with perennial grasses and legumes, oribatide became prevalent

Influence of sewage sludge from iasi water treatment station on soybean yield quantity and quality and soil chemical characteristics

The fermented sewage sludge from Iaşi Municipal Treatment Station, by its chemical and biological characteristics can be used as fertilizer on most of soils, except the salted soils, due to high content of soluble salts (1.0 g/100 g dry sewage sludge) and amendment measures, necessary in these cases. The use of fermented sewage sludge in soybean crop, at a rate of 40 t/ha, resulted in getting mean yield increases of 50 % (813 kg). Heavy metals content from fermented sewage sludge at the Iaşi Municipal Treatment Station was higher at zinc (3620 ppm) and copper (53 ppm), requiring the limitation of sewage sludge rate to 20-30 t/ha. The concentration of heavy metals in seeds obtained from soybean treated with 40 t/ha sewage sludge was higher (compared to untreated control) with 5.3 ppm at Fe, 0.92 ppm at Cu and with 0.01-0.07 at Zn, Mn and Ni. The other analysed heavy metals (Cr, Pb, Cd, Co, As, Hg) were not found in soybean seeds, treated with 40 t/ha sewage sludge. The concentration of heavy metals registered in soybean seeds, fertilized with 40 t/ha sewage sludge, has shown that these values did not exceed maximum allowable concentration established by Directive of EC no. 466/2001

Investigations on the influence of crop rotation and organo-mineral fertilization on maize yield and physicalchemical characteristics of cambic chernozem in the Moldavian Plain

The paper presented the results of investigations concerning the influence of long-term fertilization (39 years) on some physical and chemical characteristics of Cambic Chernozem from the Moldavian Plain and on the yield of maize, placed under different crop rotations with perennial grasses and legumes. The 39 year use of the crop rotation peaswheat- maize-sunflower+reserve field, cultivated with perennial grasses and legumes, has resulted in getting maize yield increase of 29% (1312 kg/ha), in comparison with maize continuous cropping. On slope lands, the high rate fertilization of maize crop (N140P100) has determined, in the latest ten years, an average yield increase of 93% (3086 kg/ha), against the control, and applying a rate of N60P40+30 t/ha manure resulted in getting a very close yield increase (95%, 3156 kg/ha). The long-term use of 4-year crop rotation + field cultivated with perennial grasses and legumes has determined a maize yield increase of 16 %, respectively, 800 kg/ha, and the improvement of physical and chemical characteristics of soil. In maize crop, fertilized with N60P40+30 t/ha manure, the rate of greater than 0.25 mm hydrostable aggregates was higher by 26%, against the control; placing maize in crop rotations with perennial grasses and legumes has resulted in increasing by 30% the rate of hydrostable aggregates, compared to maize continuous cropping. The 39 year use of 3 and 4-year crop rotations, which had perennial grasses and legumes in the crop structure, has determined the increase in the content of total carbon and mobile phosphorus from soil by 10% (1.7 C g/kg), respectively, 31% (11.8 P-AL mg/kg), in comparison with maize continuous cropping. A minimum supply level of mobile phosphorus in soil (37-72 ppm) in maize continuous cropping (39 ppm) and wheat-maize rotation (37 ppm) was maintained in case of annual application of a rate of N100P80. The total carbon content in Cambic Chernozem from the Moldavian Plain has registered significant increases at higher rates than N140P100, in case of organo-mineral fertilization and 4-year crop rotation + reserve field cultivated with perennial grasses and legumes. In maize continuous cropping and wheat-maize rotation, very significant values of the carbon content were registered only in case of organo-mineral fertilization, and in 4-year crop rotation + reserve field, cultivated with perennial legumes, in case of N140P100 fertilization

Effects of long-term fertilization on the fertility of erosion-affected soils from the Moldavian Plateau

The paper presented the results of investigations concerning the influence of long-term fertilization (43 years) on some chemical characteristics of Cambic Chernozem from the Moldavian Plain and on the maize yield. On slope lands, the high rate fertilization of maize crop (N140P100) has determined, in the latest ten years, an average yield increase of 103% (3373 kg/ha), against the control, and applying a rate of N70P70+40 t/ha manure resulted in getting a very close yield increase (99%, 3258 kg/ha). The minimum supply level of mobile phosphorus in soil (37-72 ppm) in pea-wheat-maize rotation (37 ppm) was maintained in case of annual application of a rate of N100P80. The total carbon content in Cambic Chernozem from the Moldavian Plain has registered significant increases at higher rates than N140P100 and in case of organo-mineral fertilization. The annual fertilization of wheat and maize, at the rate of 70 kg N + 70 kg P2O5/ha + 6 t/ha stalks of wheat, has determined, compared to the unfertilized variant, the increase in the content of organic carbon from soil by 14.5% (2.4 g organic C/kg) on weakly eroded soils, and by 29.5% (4.2 g organic C/kg) on highly eroded soils. During the long-term fertilizing of wheat and maize with high rates of mineral fertilizers (N140P100), on highly eroded lands, the total content of carbon has increased by 16.9% (2.4 g organic C/kg soil), against the unfertilized control. Applying moderate rates of mineral fertilizers (N70P70), together with 60 t/ha manure, has determined, after 43 years of testing, the increase by 32% (5.3 g organic C/kg) in the content of organic carbon from soil, on weakly eroded soils, and by 42.3% (6.0 g organic C/kg soil) on highly eroded soils, compared to the unfertilized control. On 16% slope arable lands from the Moldavian Plateau, the mean annual soil losses by erosion, registered during 1986-2007, were of 1.640 t/ha in winter wheat, 4.618 t/ha in beans, 1.89 t/ha in the field cultivated with perennial grasses and legumes on the second year of vegetation, 9.176 t/ha in maize and 9.6 t/ha in sunflower