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A pot experiment was conducted to assess the fertilizer value of ten digestates obtained from typical agricultural substrates (DA), and with the addition of waste from the agri-food industry (DW). The test plant was maize. The digestates obtained from typical agricultural substrates contained more N, P and Cu, and the digestates from co-fermentation of farm residue with organic industrial waste contained more K, Mg, Ca, Zn, Fe and Mn. The heavy metals present in the digestates did not exceed (except iron) their respective amounts found in unfermented pig slurry. The maize-growing experiment proved the positive effect of digestates on maize yields, which were more than three times as high in the DAfertilized combinations (mean 377.45 g f.m./pot) and more than twice as high in the DW-fertilized combinations (mean 223.25 g f.m./pot) as in the control combination (105.25 g f.m./pot). It is concluded that the tested digestates can be recommended for agricultural use, but their fertilizer value will depend mainly on their nitrogen content. When assessing the fertilizer value of digestates, the important issue is to focus on balancing the potassium dose introduced into the soil with the digestate rather than concentrating only on nitrogen or the monitoring of heavy metals content. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted to assess the fertilizer value of ten digestates obtained from typical agricultural substrates (DA), and with the addition of waste from the agri-food industry (DW). The test plant was maize. The digestates obtained from typical agricultural substrates contained more N, P and Cu, and the digestates from co-fermentation of farm residue with organic industrial waste contained more K, Mg, Ca, Zn, Fe and Mn. The heavy metals present in the digestates did not exceed (except iron) their respective amounts found in unfermented pig slurry. The maize-growing experiment proved the positive effect of digestates on maize yields, which were more than three times as high in the DAfertilized combinations (mean 377.45 g f.m./pot) and more than twice as high in the DW-fertilized combinations (mean 223.25 g f.m./pot) as in the control combination (105.25 g f.m./pot). It is concluded that the tested digestates can be recommended for agricultural use, but their fertilizer value will depend mainly on their nitrogen content. When assessing the fertilizer value of digestates, the important issue is to focus on balancing the potassium dose introduced into the soil with the digestate rather than concentrating only on nitrogen or the monitoring of heavy metals content. [ABSTRACT FROM AUTHOR]

The effect of continuous application of mineral fertilizers with and without farmyard manure (FYM) and lime on phosphate sorption and soil-test phosphorus were studied in a long-term field experiment on a sandy loam soil. Regular application of manure and increased Corg content significantly increased the amounts of ammonium oxalate extractable Alox and Feox in the soil. At the same time, in the combinations with FYM, there was a significant (30%) reduction in one-point P sorption index (PSI) relative to the combinations without manure. The negative correlations of PSI with Alox, Feox and Corg may indicate that the specificity of the organic compounds originating from manure were the reason for the reduced activity of Feox and Alox in phosphate sorption. Liming significantly reduced the capacity for phosphorus retention and decreased the PSI by 21% by reducing Feox and Alox contents, increasing the amounts of interchangeable forms of Ca and K, and above all by significantly reducing the amount of (Alex). Regular application of manure caused a greater increase in the readily available P pool of water (P-WE) and calcium chloride (P-CaCl2) extractable P, than in the more recalcitrant P of double lactate (P-DL) and ammonium oxalate (Pox) extractable P. A reverse trend was found in the combination with TSP. The ammonium oxalate P saturation index (PSIox) increased in proportion to the amount of phosphorus supplied as FYM and TSP. The smaller amounts of phosphorus introduced with manure (25% of the amount supplied with TSP) caused PSIox to increase from 32% in the soils without FYM to 35.8% in those with FYM. The annual application of TSP at 50 kg/ha for more than 40 years increased PSIox from 36% in the combinations without TSP to 46% in those with TSP. [ABSTRACT FROM AUTHOR]

The research aimed at the assessment of N2ON emissions from agricultural soils subjected to different soil pH conditions. It was conducted on the basis of three long-term field experiments in Skierniewice in Central Poland, maintained with no alterations since 1923. The investigation was carried out on limed (CaNPK) and acid (NPK) treatments. Measurements were conducted during the growing periods of 2012 and 2013. N2O-N emissions from the soil were measured in situ by means of infrared spectroscopy, using a portable FTIR spectrometer (Alpha, Bruker). Regardless of crop rotation, the N2O-N emissions from similarly treated, permanently (since 1923) acid and limed soils were similar. In the climate, soil and agricultural conditions of Central Poland, two optimum soil pH ranges with the highest N2O-N emissions are predicted (pH 4.3-4.4 and pH > 6.6). Liming of longterm limed treatments (CaNPK) does not increase soil N2O-N emissions. The relationship between soil pH and N2O-N fluxes is relatively well described by a linear regression equation only for limed soils, but not for acid soils. [ABSTRACT FROM AUTHOR]

The paper presents the results of a two-year study (2012 and 2013) on the levels of DOC and N-NO3- in drainage water in long-term fertilization experiments (since 1923) in Skierniewice, central Poland. The study was conducted within three different systems of fertilization: mineral, mineralorganic and organic. On average, the highest concentration of DOC in drainage water was found in the organic fertilization system, lower in the mineral-organic, and the lowest in the mineral fertilization system. By contrast, the concentration of N-NO3- in drainage water was found to be higher in the mineral-organic system than in the organic and mineral fertilization systems. The highest concentration and leaching of N-NO3- in drainage water was found to occur in early spring. Nitrogen losses through leaching ranged from approx. 8 to 15 kg N/ha in the mineral fertilization system, and from approx. 21 to 38 kg N/ha in the mineralorganic system, and were higher in the year with greater total precipitation. In the organic fertilization system, by comparison, those losses were similar in both years of the study and amounted to approx. 22 kg N/ha. During the period of the most intense leaching of nitrogen from the soil, the flux of N-NO3- was accompanied by insufficient amounts of DOC necessary for highly effective denitrification. The ratio DOC/N-NO3- in drainage water during the intense leaching of nitrates indicated that approx. 38.5% of the N-NO3- load in the mineral system, approx. 27.1% in the mineral-organic system, and approx. 40.6% in the organic fertilization system could potentially have undergone denitrification. This means that approx. 60-70% of the nitrogen washed out from agricultural fields can permanently contaminate the hydrosphere. [ABSTRACT FROM AUTHOR]