ROCZNIKI GLEBOZNAWCZE T. X X X V II, NR 1, S. 49—65, W ARSZAW A 1986
F R A N C IS Z E K M A C I A K , H O R S T S Ö C H T IG
RELATIONSHIPS BETWEEN THE TRANSFORMATION OF ORGANIC COMPONENTS TO CARBON DIOXIDE EVOLUTION AND NITROGEN
MINERALIZATION IN PEAT SOILS Agricultural University o f W arsaw , Poland Institute o f Plant Nutritiiom and Sc.il Science,
Braunschweig (FRG)
IN T R O D U C T IO N
The problem of an appropriate management und utilization sys tems of peat soils constituted the subject of an intensive research for over 100 years. The problem arose in connection with the necessity of de veloping new areas for agricultural production as well as the need to protect all peat soils against decomposition and the rapid loss of organic matter. To significant factors affecting phisical, chemical and biochemi cal changes in peat soils as well as decomposition of organic matter be long reclamation, tillage, crop rotations and fertilization [3, 9, 10].
It is generally believed that soils undergo the strongest humification and mineralization under the field crop production system and conside rably less under the grassland system. This is due to the more intensive aeration of the peat soil profile under field conditions and the smaller accumulation of plant residues in case of the grassland system, especially in the upper layers of the soil profile- Under good aerobic conditions of decay the soil microorganisms quickly utilize more readily degradable materials converting them to carbon dioxide and mineral nitrogen or in corporating them into their own structural matter [11].
The resistant materials, particularly lignins and bitumens, tend to accumulate in peat soils [4, 9, 10]. Decomposition occurs parallelly to the peat-forming plant residues as well as the residues derived from the new plants resulting from crop production. The recent organic matter accumu lates in the soil and probably affects the decomposition rate of the orga nic matter already present [11]. Under good climatic and aerobic condi tions the amount of humic acids, total and mineral nitrogen as well as ash increase rapidly while the content of carbohydrates decreases. [4, 9,
50 F- Maciak, H. Söchtig
In the paper its authors present the results of their studies concerning effects of a 25-year term and various agricultural systems of peat soil cultivation. Various biochemical changes in soils and their response to mineralization of organically bound carbon and nitrogen have been noted.
M A T E R IA L S A N D M E T H O D S
Materials consisted of low peat soil samples taken from the depth of 5— 10, 25— 30, 55— 60 and 95— 100 cm on soil sites of the Peat Experiment Station Biebrza, Poland. The peat soils were used for the past 25 years (1957— 1982) for grassland, field or alternate (fieldgrassland) cultivation with varying mineral fertilization. One of the peat soil sites was for 80 years under forest.
Utilization and treatments : — grassland — O, K, PK, NPK, — field - O, K, PK, NPK,
— alternate utilization (3 years field and 3 years grassland) — O, K, PK, NPK,
— forest — (one profile) — O. Fertilization:
О — without fertilization, К — 83 kg К per ha a year,
PK — 83 kg K, 22 kg P per ha a year,
NPK — 83 kg K, 22 kg P, 30 kg N per ha a year.
Plants in the alternate utilization: 1. potatoes, 2. hemp, 3. summer rye, 3 years grassland.
Plants in the field utilization: typical mixture of grasses adapted to peat-soil conditions.
Forest: peat soil under birch forest for about 80 years. Analytical methods:
The peat kind and the peat decomposition degree (in fresh samples) was determined by the microscopic method, while the pH value (in НЮ) was measured potentiometrically.
Milled and sieved ( 0 2 mm screen) air-dry peat soil samaples were used for further analyses.
Organic matter and ash contents were determined by burning peat samples at the temperature of 550°C.
Carbon content was determined by the dry combustion method and nitrogen — by the micro-Kjeldahl method.
Humus fractions were determined according to K o n o n o v a and B e l c h i k o v a [8].
Carbohydrate (collulose and hemicellulose) — according to S t e v e n s o n [17].
Relationships between the transformation... 51
Measurement of the C 0 2 secretion was done after N o r m a n and N e w m a n [12]. Soil samples were incubated at 32°C in l-liter bottles
and the CO2 secreted was absorbed in a 0.5 N NaOH solution. Periodical
titration with 0.5 N HC1 was carried out after the addition of an excess amount of 3 N BaCl2 to determine the level of unneutralized NaOH.
The amount of C 02 secreted from soil was calculated as the difference from the control.
Mineralization of nitrogen was determined after the S t a n f o r d and H a n w a y [16] technique of longterm incubation (at 32°C) with inter mittent (2-week-intervals) leaching. Peat soil samples were sieved to aggregate size ± 0 4 mm. After each leaching procedure excess water was removed by means ;of the water jet pump at a suction of 0.5 bar-
N— NH4 and N— NO3 as the final products of N-mineralization were de
termined after В r e m n e г [2].
IN V E S T IG A T IO N R E S U L T S
S o m e g e e b o t a n i c a l a n d c h e m i c a l p r o p e r t i e s o f s o i l s . The soils examined (mucky peats and peats) represented reclaimed low peat soils from north-eastern parts of Poland. Due to the source of the data (Table 1) the discussed peat soils are typical representatives of low peat soil profiles consisting mainly of sedge, reed or sedge-reed peat.
The pH values of the soils varied within the limits of 4.5— 5.9. The pH of upper layers was usually less than 5.0. Systems of agricultural cul tivation did nor affect the acidity of peat soils. The peat decomposition degree ranged from low (25%) trough medium (50%) to high (over 60%). Decomposition of peat organic matter often depends on the depth, with the upper layers of soil profiles, as a rule, often being more decomposed than deeper ones. The decomposition of the peat is also affected by the kind of peat and the crop production system.
As shown by the data presented in Table 1, the cultivated, grassland and forest soils are stronger decomposed than the other soils.
The long-term cultivation of soil, particularly of the grassland and fo rest sites, led to an increase of ash and a decrease of organic matter. This was observed particularly clearly in upper soil layers.
From the data presented graphically in Fig. 1 it can be observed that the greatest increase of the ash content occurred in unfertilized grassland soils and the same soils receiving additionally K. Significant increase of the ash content was also visible in unfertilized soils in the field aaid al ternate
utilization-The lowest values of the ash content occurred in the PK-fertilized site. Fertilization decreased the average ash content in soil in all cases of the field cultivation...
F. Maciak, H. Söchtig
Analyses of soil samples for the content of humic acid showed distinct differences depending on the decomposition of the soil organic matter and the cultivation system.
More humic acids were formed in the strongly decomposed (mostly) surface layers of soil profiles than from deeper layers. However, in some soils the deepest layers of the profile contained the greatest amount of humic acids. As presented in Fig. 1, the average content of humic acids
Fig. 1. A verage content of ash, humic acids and carbohydrates in peat soil profiles
in soil depended on the cultivation and fertilization method. An intensive humification process took place in soils under alternate utilization, ferti lized PK and К or unfertilized. However, the greatest average content of humic acids was noted in NPK-fertilized soils in the field or forest sites. Grassland soils fertilized showed also stronger humification than the other grassland soils.
It is clear from the data mentioned that nitrogen and NPK fertiliza tion stimulates the humification process of peat soils. However, the effect of the remaining К and PK fertilizers is questionable.
The results of the analyses for carbohydrates (Table 1) indicate that the content of cellulose and hemicellulose in peat soils depends on the soil decomposition degree and the profile depth. The cllulose content varied
Relationships between the transformation... 53
within 0.33— 2.05%, the hemicellulose content — within 3.16— 8.58% of dry matter of soil. With regard to the total carbohydrate content, the lo west content of cellulose was found -in upper layers as compared with deeper soil layers. Conversely, the highest content of hemicellulose was
T a b l e 1 d a t a o f p e n t s o i l s r , 0 . Jia.vcr c:: Kind с Г pset I Decom p o si tio n dofri'oe f' I...
A oh b a tte rСrpanic Iluraicacida
Ca]:h o !:jd ra te ce llr.r lo ss h e * ic e l l u -1029 t o t a l % o f d . c . • i i s i ; { •• ... ! 5 6 7 II 3 II 9 !1 10 II 11 ' G raso Ian?. r it e С 1 5 -1 0 4 ,3 дне!: VO 1 6 ,1 3 8 3 ,3 7 2 3 ,6 9 0 ,3 3 8 ,4 5 8 ,7 3 2 2 5 -3 0 5 ,0 ced^o-peat 40 9 ,4 6 9 0 ,5 4 2 0 ,2 7 1,51 5 ,0 3 6 ,5 4 3 5 5 -6 0 5 ,0 re ed-sc dre peat 50 1 1,46 6 5 ,5 4 1 9 ,3 2 1 ,0 2 3 ,7 7 4 ,7 9 4 2 5 - '0 0 5 ,2 reed Р'З e » Co 1 5 ,3 3 6 4 ,6 7 2 3 ,8 0 1 ,0 7 3, 16 4 ,2 3
a*ïtlan d s i t e К
5 5 -1 0 4 ,o muck 70 1 4 ,6 3 £ 5 ,3 7 2 4 ,2 1 0 ,9 4 8 ,2 4 9 ,1 8 6 2 5 -3 0 5 ,1 sedc3 peat 35 11, SS 8 8 ,в 4 1 3 ,9 9 1 ,5 3 5 ,9 7 7 ,5 0 7 5 5 -3 0 5 ,2 reed -sedçe poat 40 1 1 ,7 4 6 8 ,0 4 1 3 ,0 5 1 ,2 6 4 ,1 5 5,41 3 9 5 -1 0 0 5 ,3 a ld er peat 45 15, C2 8 4 ,9 3 2 3 ,1 1 1 ,4 3 3 ,8 3 5 ,3 7 1 1 Grassland c it e ГК * 9 5 -1 0 5 ,1 icucl: 70 1 6 ,7 0 8 3 ,3 0 2 2 ,0 3 0 ,7 4 8 ,5 8 0 -i? I 2 5 -3 0 5 ,3 red^c гг at 50 1 0 ,7 2 8 9 ,2 6 1 6,25 1 ,6 3 4 ,3 5 6 ,4 3 ! -.1 5 5 -6 0 5 ,1 rcsd pint 40 1 2 , ?8 6 7 ,0 2 2 1 ,2 0 0 ,9 5 4 ,5 0 5 ,4 5 12 3 5 -1 0 0 5 ,2 I reed pebt I 40 1 0 ,4 7 8 9 ,5 3 1 2,75 1,0 5 4 ,7 6 6,61 Graf3a2and e ite 1ГРК 13 5 -1 0 4 ,8 EU С к 70 13,61 8 6 ,3 9 31,01 0 ,6 8 8 ,0 2 8 ,7 0 14 2 5 -3 0 5 ,1 reed-Eeć£T2 peat 40 10 ,4 3 8 9 ,5 2 2 3 ,5 0 0 ,4 6 5 ,8 7 6 ,3 3 15 5 5 -6 0 5 ,2 T6ed peat 35 1 2 ,0 0 8 7 ,5 3 2 3 ,6 4 0 ,8 0 3 ,7 3 4 ,5 3 16 S 5-100 5 ,4 KG8C peut 25 1 2 ,0 3 8 7 ,1 7 1 6 ,7 0 1 ,5 7 4 ,3 9 5 ,9 6 Alternateï u t i l i z a t ion c ite 0
17 5 -1 0 4 ,9 sod^’c pent 60 1 4 ,4 3 8 4 ,5 7 2 6 ,6 7 0 ,5 6 8 ,0 7 8 ,6 3 :u 2 5 -3 0 5 ,0 cedgo pebt 40 1 3 ,2 0 8 6 ,8 0 2 2 ,4 9 1 , 5 2 5 ,6 1 7 ,1 3 19 55-C0 4 ,9 recd-sed^.e peat 40 10 ,9 6 Г ?,С 4 2 3 ,5 2 1,3 7 3 ,9 4 5,31
20 9 5 -1 0 0 5c 5 reed p? гЛ 45 1 3 ,3 2 8 0 ,6 8 2 6 ,8 5 1 ,5 7 4 ,4 2 5 ,5 9 A ltern ate u t i l i z a t i o n n ite К
21 5 - 1 0 4 ,3 csdge peat 55 1 4,30 8 5 , 6 2 2 9 ,5 7 0 ,2 7 8 ,0 5 9 ,02 22 2 5 -3 0 4 ,9 Bedge-аогБ peat 30 1 0 ,0 2 8 9 ,9 3 2 2 ,7 2 1 ,2 4 5 ,1 6 6 , 4 0 23 55 -6 0 5 .1 eedfc-a peat 45 1 1 ,0 2 8 8 ,9 3 2 2 ,9 4 1 ,0 2 4 ,4 5 5 ,4 7 24 95 -1 0 0 5 ,4 a ld er peet 60 13,51 3 6 ,4 9 31,01 0 ,4 3 3 ,7 0 4 ,1 3 A ltern ate u t i l i z a t i o n s i t e PX 25 5 -1 0 5 .0 eedge-aoes peat 45 1 3 ,0 0 8 7 ,0 0 2 5 ,8 0 0 ,5 1 7 ,0 3 7 ,5 4 26 2 5 -3 0 5 ,3 codge peat 35 14 ,3 3 0 5 ,6 7 19 ,3 5 0 ,8 3 5 ,0 5 5 ,9 3 27 5 5 -6 0 5 ,2 cedge-xeed peat 40 1 1 , 6 2 8 8 ,3 8 2 6 ,7 0 o , d 3 ,9 9 4 ,3 0 23 9 5 -100 5 ,1 reed por.t 45 11,51 8 8 ,4 9 3 3 ,5 2 1,31 3 ,9 9 5 ,3 0
54 P. Maciak, H. Söchtig Tabla 1 co n tin u el 1 2 3 ; - 4- - 5 6 I: . 7 II 8 I 9 г io iI 11 ? A ltern ate u t i l i z a t i o n s i t e ЯРК j 29 5 -1 0 4 ,9 sedge peat 60 1 3 ,8 3 8 6 , 1 2 30,51 0 ,9 2 6 ,3 2 7 ,2 4 j 30 2 5 -3 0 5 ,2 sedge peat 50 1 0 ,9 2 8 9 ,0 8 2 4 ,4 8 1 ,0 7 7 , 0 0 8 ,0 7 j 31 5 5 -6 0 5 ,2 sed ge-reed peat 40 1 2 , 6 6 8 7 ,3 4 19,21 1 ,4 7 4 ,9 1 6 ,3 8 j 32 9 5 -1 0 0 5 ,4 reod peat 60 2 1 ,5 9 7 8 ,4 1 14 ,7 8 0 ,7 8 3 ,7 2 4 ,5 0 j
F ie ld s i t e 0
33 5 -1 0 4 ,8 sedge peat 55 1 2 ,8 5 8 7 ,1 5 2 1 ,5 3 0 ,3 4 7 ,3 3 8 , 2 2
34 2 5 -3 0 4 ,9 reed peat 50 1 0 ,7 4 8 9 ,2 6 1 6 ,3 4 1 ,0 7 5 ,4 5 6 ,5 2 35 5 5 -6 0 5 ,1 sed ge-reed peat 55 12 ,0 4 8 7 ,9 6 1 8 ,0 4 1 ,31 4 , 0 2 5 ,3 3 i 36 9 5 -1 0 0 5 ,0 roed peat 70 17 ,0 9 8 8 ,9 1 2 4 ,S9 1 ,0 5 3 ,2 3 4 ,2 8 j F ie ld s i t e X i\ 37 5 -1 0 4 ,6 sed£3 peat 60 13 ,7 5 8 6 ,2 5 2 4 ,3 0 1 ,0 4 7 ,9 2 i 8 ,9 6 ! 38 2 5 -3 0 5 ,2 sedge peat 40 1 2 , 1 0 8 7 ,9 0 1 9 ,6 4 1 ,7 3 5 ,7 3 7 ,4 6 j 3? ; 5 5 -6 0 4 ,8 sed ge-reed peat 35 1 0 ,4 3 3 9 ,5 7 19 ,0 3 0 ,8 5 4 ,8 5 5 ,7 0 40 jj 9 5-1 0 0 5 ,4 raed peat 65 14,1*3 8 5 ,8 4 24,8 8 0 ,9 4 3 ,7 1 4 ,5 5 j !I ! \ F ie ld s i t e PS j 41 5 -1 0 4 ,9 sedge peat 50 1 4 ,0 7 8 5 ,3 3 2 1 , 2 6 0 ,5 0 7 ,7 2 3 ,6 2 j 42 2 5 -3 0 5 ,1 aodge-reed poat 40 9 ,0 5 9 0 ,9 5 1 6,96 2 , 1 2 4 ,9 8 7 ,1 0 ! 43 5 5 -6 0 5 ,0 sed ge-roed peat 35 1 1,65 8 5 ,3 5 23 ,1 8 0 ,5 5 4 ,2 5 4 ,8 0 j 44 95*100 5 ,1 reed peat 45 9 ,7 7 9 0 ,2 3 2 0 , 1 6 2 ,0 5 5 ,5 7 5 ,6 2 ! i F ie ld s i t e 5PX 45 5 -1 0 4 ,8 sedge peat 35 1 2, 26 8 7 ,7 4 26 ,4 6 0 ,4 4 7 ,4 9 7 ,9 3 46 2 5 -3 0 5 ,0 sedge peat 30 1 0 ,9 2 8 9 ,0 8 2 5 ,9 7 1 ,4 0 5 ,2 3 6 ,6 3 47 5 5 -6 0 5 ,2 zeed peat 40 11,91 8 3 ,0 9 3 1 ,6 8 0 ,2 4 4 ,3 4 4 ,5 8 43 9 5 -1 0 0 4 , 9 a ld er peat 60 14 ,9 2 8 5 , 0 8 3 0 ,6 0 1,1 7 4 ,1 1 5 ,2 3 Forest s i t e 0 49 5 -1 0 4 ,5 a ld e r peat 60 1 5 ,0 7 8 4 ,9 3 3 1 ,0 5 0 ,5 9 7 ,4 0 7 ,9 9 50 2 5 -3 0 4 ,9 a ld e r peat 40 9 ,0 4 9 0 ,9 6 2 2 ,6 9 1, 6 1 6 ,5 3 8 , 1 4 51 5 5 -6 0 5 ,2 a ld e r peat 50 10 , 2 1 8 9 ,7 9 2 0 ,0 8 1 ,0 7 4 ,4 5 5 ,5 2 52 9 5 -1 0 0 5 , 4 a ld e r peat 60 1 9 ,8 5 8 0 ,1 5 3 0 ,0 0 0 ,5 5 3 , 6 6 4 ,2 1
in upper soil layers with a distinct decrease down the profile. This is op posite to the cellulose content, which was very low in upper soil layers and increased down the profile.
The above differences are affected further by cultivation. As given in Table 1, the total carbohydrate content varies in upper layers of soil from 7.24 to 9.32% of dry matter. The lowest values of carbohydrates (about 4.13%) were noted in the deepest soil layers.
The data presented prove (Fdg. 1) that soils fertilized with К and PK under grassland and field utilization are richest in carbohydrates. The lowest values of carbohydrates were found in unfertilized soils and field soils receiving additionally NPK. The PK-fertilized soil under alternate utilization contained also low carbohydrate amounts. As shown in Fig. 1,
Relationships between the transformation... 55
a decrease of the carbohydrate level resulted often in increased level of humic acids in the soils investigated.
Significant elements characteristic for particular soil-forming pro cesses of the profile, include differences in the total carbon and nitrogen content (Table 2).
Ta b l e 2
Carbon and nitrogen content and r a t io o f scae coaponenta o f peat s o i l
Sample No. С % T o ta l N o f d .a . С 7T H em icelluloee С09/ е т о 1 . / carbohydrateT o ta l H-SO, C ollu loa e It /m in / C0 2 / e y o i . / 1 2 3 4 5 6 7 8 Grassland s i t e 0 1 44 ,2 9 4 ,4 3 9 ,9 9 2 5 ,4 4 4 ,0 5 4 ,5 6 3 ,7 6 2 4 3 ,9 8 3 ,3 9 1 4 ,4 4 3 ,3 4 5 ,0 4 4, 6 2 2 ,8 7 3 47,98 3 ,2 5 1 4 ,7 5 3 ,7 2 3 ,2 3 3 ,9 3 3 ,8 5 4 4 6 ,5 9 2 ,5 4 1 3 ,3 2 2 ,9 5 4 , 2 0 4 ,8 4 4, 2 0 Grassland s i t e X 5 4 6 ,9 0 3 ,9 0 1 1 ,3 4 3 ,7 9 7 ,2 3 4, 6 0 2 ,9 7 j 6 48 ,8 0 3 ,3 9 1 4 ,4 0 3 ,9 0 5 ,8 3 4 ,9 5 4 ,6 6 I 7 4 7 ,4 6 3 ,3 3 1 4 ,2 4 3 ,2 8 6,'33 4 ,0 7 3 ,1 4 8 5 2,28 2, 6 6 1 9 ,6 2 2,S2 3 ,S 0 5 ,6 0 3 .2 7
J
Grassland a lte PK I 9 4 8 ,8 7 4 ,1 6 1 1 ,7 4 1 1 ,5 3 4 ,9 1 4 ,6 5 4 ,0 7 10 49 ,4 5 3 ,2 8 15 ,0 7 2 ,9 7 6 ,5 9 4 , 0 2 4 ,1 7 11 5 0 ,7 0 3 ,5 3 1 4 ,1 7 4,7 1 5 ,9 6 3,66 2 ,2 3 12 4 8 ,6 9 2, 6 6 1 3 ,3 0 2 ,5 8 4 ,5 7 7 ,6 7 5 ,4 2 Grassland s i t e H?X 13 4 5 ,8 0 4 ,1 9 1 1 ,0 4 1 1 ,7 9 6 ,7 5 3 ,5 9 4 ,3 5 14 4 9 ,2 3 3 ,8 0 1 2 ,9 5 1 2 , 8 8 8 , 0 1 3 ,3 4 2 ,7 0 15 46,31 3 ,5 4 1 3 , 0 6 4 ,6 4 5 ,2 3 2 ,7 9 7 ,1 3 16 4 4 ,6 9 2 ,8 2 1 9 ,3 9 2 ,8 0 7 ,3 8 4 ,0 9 8 , 6 1A ltern ate m tili z a t i o n a lte 0
17 4 4 ,2 7 4 ,1 1 1 0 ,7 7 1 4 ,3 5 7 ,3 6 4 ,1 4 2 ,6 4 13 5 2 ,1 9 3 ,3 7 1 5 ,4 8 6,68 6 ,0 3 6 ,0 8 2,8 1 19 4 3 ,6 9 3 ,7 0 1 3 ,1 4 2 ,8 7 3 ,2 5 4 ,5 9 4,91 20 50, 0 6 2 ,8 7 1 7 ,4 3 2 ,8 2 4 ,7 0 6 ,2 7 2 ,4 2 A ltern ate u t i l i z a t i o n 9l t e К 21 4 3 ,4 7 3 ,7 3 11,66 8 , 3 3 6 ,0 7 4 ,5 2 0 , 7 2 22 4 7 ,4 7 3 ,6 9 1 3 ,0 2 4 ,1 6 6 ,1 3 4 ,9 7 1 ,2 5 23 49 ,9 2 3 ,7 3 1 3 ,3 7 4 ,3 8 3 ,2 3 4 ,2 8 4 ,0 8 24 4 5 ,1 3 2 ,9 1 1 5 ,5 2 8 , 5 4 3 ,7 2 4 ,5 6 2 ,4 9
A ltern ate u t i l i z a t i o n a lte PK
25 4 5 ,9 8 3 ,7 7 1 2 ,0 5 1 3 ,7 2 7 ,2 5 3 ,5 3 5,2 2
26 4 7 ,5 3 3 ,4 7 13,51 5 ,7 3 5 ,6 7 3 ,3 5 1 9 ,8 0
27 4 3 ,1 0 3 ,3 7 14 ,2 5 4 ,9 5 4 ,3 0 2 ,7 5 6 ,9 1
56 F. M aciak, H. Söchtig 1 2 3 4 ' 5 I! 6 !i 7 !i ß Altern ate u t i l i z a t i o n s it e КГл 29 4 7 ,2 0 4,1 8 11 ,2 8 6 ,9 0 10 ,7 8 3 ,4 9 2 ,0 9 30 4?, 91 3 ,2 3 1 5 ,1 4 6 , 5 2 6 , 0 6 4 ,7 8 2 ,5 3 31 46 ,2 0 3 ,4 7 1 3 ,2 9 3 ,3 5 5 ,2 7 3 ,7 4 7 ,1 0 32 4 3 ,1 3 1,S2 22 ,4 2 4,7 4 6 ,8 1 3 , 1 6 2 , 1 2 F ie ld s i t e 0 33 4 7 ,4 7 3 ,9 0 12 ,1 8 6 ,7 4 7 , 6 6 4 ,4 5 14,66 34 49,61 3 ,3 4 14 ,8 7 5,11 3 ,0 4 5 ,1 3 23 ,0 6 35 47,71 3,S 2 1 2 ,4 3 3 ,0 7 4 ,8 2 4,4 1 3 ,5 3 36 46,43 2 ,6 3 1 7 ,6 7 3 , 0 6 4 ,3 5 5 ,5 4 3 ,21 F ie ld e ite К 37 4 5 ,4 3 4 , 1 2 1 1 , 0 1 7 ,5 9 6 ,7 2 4 ,4 5 4 ,2 3 38 4 8 ,2 7 3,31 1 4 ,5 6 3 ,3 0 8 , 7 2 4 , GO 2 ,5 7 39 4 7 ,2 3 3 ,5 5 13 ,2 9 5 ,6 7 5 ,5 2 3 ,4 4 1 .1 9 40 4 7 ,9 7 3 ,1 3 1 5 ,3 2 3 ,9 2 6, 6 8 4 ,2 4 2 , 2 2 F ield s i t e PK 41 4 3 ,2 3 3,S 6 1 2,1C 8 ,5 3 8 ,8 2 4 ,3 1 5 ,4 5 42 4 4 ,5 7 3 ,4 5 1 2 ,9 3 2 ,3 5 5 ,2 5 4 ,7 8 1 5,38 43 4 7 ,9 4 3 ,4 9 1 3 ,7 3 7 ,7 4 3 ,8 3 4 ,2 7 3 ,7 0 44 48 ,6 8 3 ,0 2 1 6 , 1 0 2 ,7 2 4 ,3 2 6 ,9 7 4 ,3 3 F ield r i t e N?K 45 4 6 ,0 3 4,11 1 1 ,2 1 1 6,07 12,98 3 ,9 3 2 , 1 0 46 5 0 ,6 3 3 ,4 7 1 4 ,5 7 3 ,7 3 6 ,4 1 4, 6 0 4 ,4 7 47 4 9 ,4 6 2 ,8 6 1 7 ,2 9 1 8 ,2 6 4 ,6 0 3 ,6 0 14,03 40 4 9 ,3 6 3 ,6 5 1 2 ,6 9 3 ,5 3 7 ,7 5 4 ,3 6 2 ,2 3 Fore et s i t e 0 49 4 3 ,4 3 3 ,7 9 1 1 ,4 6 12, 46 6 ,7 3 3 ,2 8 4 ,0 6 50 4 8 ,2 7 3 ,4 6 1 3 ,9 3 4 ,0 5 6 , 5 2 4 ,4 6 1 ,2 0 51 4 6 ,7 9 3 ,0 4 15,38 4 ,1 4 4 ,5 6 3 ,9 8 3 ,6 4 52 4 6 ,6 3 3 ,1 7 1 4 ,7 2 6 ,5 8 3 ,7 1 4 ,0 4 9 ,06
The soils analyzed contained from 43,13 to 52-28% of total carbon and from 1.92 to 4.43% of total nitrogen. Upper layers were richer in total ni trogen than deeper ones. The C/N ratio in soils ranged from about 1 :10 in upper layers to about 1:22 in deeper ones, mostly from 1: 11 to 1 : 15.
M i n e r a l i z a t i o n o f c a r b o n a n d n i t r o g e n i n s o i l s . Chan ges in peat soil organic matter connected with its agricultural utilization exerted a distinct influence on organic matter mineralization.
The 20-week soil incubation (at 32°C) revealed differences in both mi neralization of carbon and organically bound nitrogen.
Fig. 2 showed that the sum of C 02 secreted from the soil samples af ter 20 weeks depended on such factors, as the soil profile depth and both cultivation and fertilization treatments. The greatest secretion of carbon dioxide occurred from soil samples taken from the first layer (5— 10 cm),
oitс OrX'Siand Alternate ui."izc!:on Field Forest
58 F- Maciak, H. Söchtig
whereas the C 0 2 gradually decreased in samples taken from deper soil layers.
The above differences in the carbon dioxide secretion are affected also by the cultivation and fertilization system. The effect is likely due to the lower or higher accumulation of plant residues as a result of cropping. Considering only the first layer of the soil profile, it can be stated that the most intensive mineralization of peat soil organic matter occurs in the surface layers of NPK-fertilized soils under grassland and forest sites.
The sum of the secreted CO2 in both soils during 20 weeks of their incu
bation reached 2400 mg C 02 per 100 g of dry matter. In upper layers of
the other soils the CO2 secretion observed reached 2000 mg C 02/100 g of
dry matter of soil. An insignificant increase of CO2 secretion to about
2100 mg was also noted in soils under alternate utilization fertilized with PK and NPK or unfertilized.
An increase of the C 0 2 secretion from samples taken from upper la yers are usually accompanied by an increase of mineralization rate of or ganic matter in deeper soil profile
layers-As presented in Fig. 3, the average content of C 02 in soil profiles is the highest in soils fertilized with NPK under the grassland of forest
si-Pig. 3. Average content of C 0 2 during the soil incubation at 32°C
tes. The lowest secretion of C 0 2 occurs from unfertilized soils of the field, alternate and grassland utilization sites.
The mineralization of organically bound nitrogen was investigated by determining both ammonium and nitrate nitrogen within the 20-week period.
60 F. Maciak, H. Söchtig
Fig. 4 shows that the ammonium nitrogen content in most soils inves tigates is similar and varies within about 5 mg/100 g of dry matter of soil.
The influence of the soil profile depth as well as the cultivation sys tem on the ammonium content was weak. This is contrary to thé nitrate nitrogen (N— NO;}), whose amounts in the soils in vestigated were high af ter 20 weeks of incubation. Some samples contained nitrate nitrogen le vels of over 100 mg/100 of dry matter of soil. Accumulation of nitrates the highest in soil samples taken from the upper layers of PK-fertilized or unfertilized grassland soils. Considerable differences in nitrifaction processses were also observed in samples taken from different horizons, such as second, third or fourth horizon of the soil profile.
An intensive mineralization of organically bound nitrogen was found in all soils investigated (Fig. 5). However, the highest average content of
Fig. 5. A verage content of mineral nitrogen a — N — N H 4, b 1— N — N O s, с — sum (N — N H 4-!-N — N 0 3) in soil profiles during 20 weeks of the soil incubation at 32°C
mineral nitrogen (after 20 weeks) was visible in unfertilized grassland, field and forest soils. A high mineral nitrogen level was found also -in PK and NPK fertilized soils under altermate utilization .
Sits Grassland Aitsrnate utilization Ficid Forest
DISCUSSION OF RESULTS
The transformation of peat soils in consequence of the agricultural utilization exerts a strong effect on the humification and mineralization process of the soil organic matter. Various agricultural methods of soil
Relationships between the transformation... 61
cultivation lead to different changes in the soil organic matter [9, 10], in crease or decrease of various soil components contained previously in the peat-forming plants. Also distinct synthesis of new compounds due to the action of microorganisms can be expected [1, 4, 10].
Beside the transformation process of peat soil organic matter an in tensive mineralization of organically bound carbon and nitrogen occurs as well [3, 4, 9, 10, 13]. However, the mineralization of peat soil depends on its transformation degree, climatic conditions and the utilization system [1, 4, 9]. In some soils the transformation and humification of soil organic matter as well as their mineralization rate were very different. It seems that one the reasons of the difference may be related to the organic mat ter humification rate, connected with the carbon/nitrogen ratio [4]. How ever, these factors are affected by the different accumulation of „new humus” in soil during its utilization.
The investigations have proved that the soil organic matter serves as an energy and nutrient source for the soil microflora. Under conditions of a high C/N ratio during the complete decomposition process, most or ganic carbon is volatilized as C 02 and only its minor part is assimilated
and incorporated into microbial bodies. On the other hand, nitrogen and other nutrients are bouind and accumulated there not being exposed to high losses [7, 11]. Consequently, the decomposition process of peat sbil organic matter leads invitably to a decrease of readily decomposable ma terial, such as carbohydrates and some proteins and to the concentration of ash, lignin and humus substances [3, 4, 10]. After a certain period, the mineralization and immobilization by microflora will be balanced, whe re upon nitrogen will become available to plants [4, 5, 13]. The use of so me agricultural methods can accelerate or retard the peat soil organic matter decomposition [6, 9, 11]. According to some [6, 14, 15], the new soil humus often decomposes at a faster rate than older humus. Undoub tedly the effect will depend on the amount of „new humus” accumulation in peat soils and also on how deep in the soil it is accumulated.
In the present study the transformation of some soils as well as the decomposition process of their organic matter were different. The minera lization of organic matter, as measured by the C 02 secretion was very in tensive in the samples taken from the surface layers of all soil profiles. The mineralization rate was the highest in the NPK-fertilized soils in the grassland utilization as well as in soil under forest. Intensive mineraliza tion of organic carbon and nitrogen also took place in samples taken from deeper soil profile layers down to 100 cm. This indicates a notable forma tion of „new humus” from plant residues in deeper layers. The use of mineral fertilizers increased the addition of „new humus” , and so incre ased the mineralization of carbon in the soil profiles considered. However, several questions still remain concerning mineralization of nitrogen, whose total content (after 20 weeks of the soil incubation) was the lowest
62 F. Maciak, H. Söchtig
in the samples taken from plots fertilized with NPK and the highest in samples taken from unfertilized soils in the grassland and forest utiliza tion. As mentioned already, unfertilized soils show a characteristic very low C/N ration. Presumably this effect is caused by carrying away nitro gen with higher yields obtained on fertilized soils.
The fertilization of grassland and field sites led to a decrease of the mineral nitrogen content in soils. However, in soils under alternate utili zation sites, fertilized with К and PK, increased the mineralization of or ganic nitrogen.
The observed ratios between some factors of soil properties in the de composition process showed some relationships (Table 2). In surface layers of the soils egsamined a high ratio of hemicellulose to cellulose has been noted.
This ratio decreased down profile depending on the soil cultivation method. In particular, the ratio of hemicellulose to cellulose is high in unfertilized soils utilized as grasslands, alternate field-grassland and fo rest. The higher ratio of hemicellulose to cellulose was also noted in some deeper layers of soil profiles, particularly under field and alternate utili zation. However, the deeper layers of soils in the grassland and some in the alternate utilization are usually characterized by low hemicellulose/ /cellulose ratios. This is due to the quicker decomposition rate of hemi cellulose than cellulose [4, 11].
The CO2/N mineral ratio in the decomposition process of peat soils is
approximately 5— 7. Higher ratio of C 02 to Nmin was noticed in surface
layers, particularly of the NPK-fertilized äoils in the field or alternate utilization.
The ratio of the content of total carbohydrates to the sum of CO* secreted within 20 weeks of the soil incubation, amounted to 4— 5. The
low ratio of carbohydrates to C 02 secreted was due to decreasing amounts
of hemicellulose in lower soil horizons. The ratio of nitrate N to ammo nium N in soils can constitute an index of their agricultural efficiency-
The higher the N— N 0 3/N—NH4 ratio in soil is usually an index of good
aerial conditions and of an intensive nitrification process. The soils inves
tigated were rich in nitrate nitrogen, the N—NO3/N— NH4 ratio being hig
her in surface than in deeper layers.
R EFE R EN CE S
[1] B r e m n e r J. M .: Studies an soil humic acids. I. T h e chem ical nature o f hu mic nitrogen. J. A g r. Sei. 46, 1957, 247— 256.
[2] B r e m n e г J. M .: M ethods o f soil analysis. Part 2. Chem ical and m icrobiolo gical properties. A m er. Soc. of A gronom y Inc. M adison, Wisconsin U S A , 1960,. 1149— 1238.
Relationships between the transformation... 63
[3] B r o w n J. F a r n h a m R. S.: The m ineral content of peat and the degree of decomposition. Proo. of the 5th Inter. Peat Congress 2, 1976, 246— 253. [4] F l a i g W. , B e u t e l s p a c h e r H., R i e t z E.: Chem ical composition and phy
sical properties of humic substances. In : G ieseking J. E. (ed) Soil com ponents: Orgainic components (vol. 1) Springer Verlag, N . Y o rk 1975, 1— 211.
[5] G r e e n l a n d D. J., О a d e s J. M .: Saccharides. In! Gieseiking J. E. (ed), Soil com ponents: Organic com ponents (vol. 1), Springer V erlag, N e w Y o rk 1975, 213— 257.
[6] J e n k i n s o n D. S .: Studies on the decom position o f plant m aterial in soil. V . The effect of plant cover ,and soil type on the loss o f carbon 14C labe led ryegrass decomposing under field conditions. J. Soil Sei. 28, 1977, 424— 434. [7] K a i n i s t o S.: A spect of nitrogen m obilization in peat. Proc. of the 5th Inter.
Peat Congress 2, 1976, 295— 305.
[8] K o n o n o v a M. M. , B e l c h i k o v a N. P.: Rapid m ethods of determ ining the humus composition o f m ineral soils extraction, Pochvovedenie 1961, 10— 75. [9] M a c i a k F .: Effect of fertilization and tillage on content of organic form s o f
nitrogen in peat soil and its humus fractions. Proc. o f the 4th Inter. Peat C on gress, vol .4, 1972, 105— 120, Otanieni, Finland.
[10] M a c i a k F., S ö c h t i g H .: E ffect o f the degree o f decomposition on the changes in the nitrogen fraction and ;phqnolic in low peat. Proc. of the 5th. Inter. Peat Congress 2, 1976, 310— 319, Poznań .
[11] M c L a r e n A. D. , P e t e r s o n G . H.: Soil Biochem istry, M arcel Dekker Inc. N ew Y o rk 1967.
[12] N o r m a n A . 'G., N e w m a n A . S.: Som e effects o f sheet erosion on soil m ic robiological activity. Soil Sei. 52, 1941, 31.
[13] P a r s o n s J. W. , T e n s l e y J.: Nitrogenous substance. In : G ieseking J. E. led plant residues in various soils of the Federal Republik o f G erm any and 1975, 263— 304.
[14] S a u e r b e c k D. , G o n z a l e s M . A .: Field decomposition of carbon 14-lab el- led plant residues in various soils of the Federal Republik o f G erm any and Costa Rica. In: Soil organic matter studies, vol. I. IntL Atom ic Energy Agency.
Vienna 1977, 117— 182.
[15] S a u e r b e c k D .: Influence of crop rotation, m anurial tretm ent and sodl til- ; lage on the organic m atter content o f G erm an sotils. Proc. o f the Lan d U S
Sem . 011 Soil Degr. 1980, 163— 179.
[16] S t a n f o r d G., H a n w a y J.: Predicting nitrogen fertilizer needs o f Iowa soils. II. A sim plified technique for determ ining relative nitrate production in soils. Soil Sei. A m er. Proc. 19, 1955, 74— 77.
[17] S t e v e n s o n F. J.: In: С. A . Blaok m odern m ethods o f soil analysis. A m er. Soc. A gron. Inc. Publ. M adison, W isconsin U S A 1965, 1238 .
Ф. МАЦЯК, X. СЁХТИГ ВЗАИМОСВЯЗЬ М Е Ж Д У ПРЕОБРАЗОВАНИЕМ О РГАН И Ч ЕС К И Х КОМ П ОН ЕН ТОВ, ВЫДЕЛЕНИЕМ ДВ УО К И СИ УГЛ ЕРОДА И М ИНЕРАЛИЗАЦИЕЙ АЗО ТА В ТОРФЯНЫ Х П О Ч В А Х Кафедра рекультивации и охраны природной среды Варшавской сельскохозяйственной академии Институт питания растений и почвоведения в Брауншвейге, ФРГ
64 F. Maciak, H. Söchtig Резюме Проводились лабораторные исследования с целью определения влияния продолжитель ности периода и разных chctcim сельскохозяйственного использования на интенсивность минерализации торфяных почв. Почвенные образцы отбирали из торфяных почв используемых в течение 25 в качестве лугов, переменных уголий и пашни. Сверх того анализировали почвенную среду исполь зуемую в течение 80 лет в качестве лесного уголья (образцы доставлялись опытной станцией Бебжа). Виды торфов и содержание в них гуминовых кислот, золы, органического вещества, углерода и общего азота, целлюлозы и гемм целлюлозы определяли совместно с анализом выделенного С 0 2 (во время инкубации торфов), а также минерализации азота. Результаты химического анализа торфов отобранных из разных почвенных сред пока зали, что система сельскохозяйственного использования торфяных почв оказывала заметное влияние на содержание указанных элементов в почве, а также на интенсивность процесса минерализации углерода и азота. Влияние сельскохозяйственного использования наблюдалось особенно четко в органи ческих фракциях почвы. Система возделывания растений сказывала особенно сильное влияние на поверхностные слои профиля. Минерализация углерода в почве происходила с высшей интенсивностью на удобряемых культурах. Минеральное, а особенно азотное удобрение приводило к повышению выделения С 0 2, одновременно снижая минерализацию азота в торфяных почвах. F. MACIAK, H. SÖCHTIG W S P Ó Ł Z A L E Ż N O Ś Ć M IĘ D Z Y P R Z E K S Z T A Ł C A N IE M S}Ę S K Ł A D N IK Ó W O R G A N IC Z N Y C H A W Y D Z IE L A N IE M D W U T L E N K U W Ę G L A I M IN E R A L IZ A C J Ą A Z O T U W G L E B A C H T O R F O W Y C H
K atedra R e k u lty w a c ji Ś rod ow isk a P rzyrod n iczego S G G W -A R , W arszaw a Instytut Żywieni, i a R oślin i G lebozn a w stw a, B rau n schw eig
S t r e s z c z e n i e
P rzep row a d zon o la b ora tory jn e dośw ia dczen ia w celu zbadania w p ły w u d łu g o ś ci okresu i różnego system u u żytk ow ania roln iczeg o na in ten sy w n ość m in eralizacji gleb to rfo w y ch .
P róbk i g leb o w e pob ra n o z siedlisk gleb to r fo w y c h u ży tk ow a n y ch przez 25 lat
ja k o laki przem ien n ie oraz pola upraw n e. Ponadto analiizowano siedlisKo g leb o w e
będące przez ok oło 80 lat w u żytkow a n iu lqśnym . P rób k i p och o d z iły z Z ak ła du
D ośw iad cza ln ego Biebrza.
G atunki to r fó w oraz za w artość w mich k w a sów h u m in ow ych , pop iołu , m aterii orga n iczn ej, w ęgla i azotu ogółem , celu lozy i h em icelu lozy rozp atry w a n o łączniej z analizą w y d z ie la ją c e g o się CO> (w czasie in k u b a cji torfó w ) i m in eralizacją azotu.
W y n ik i chem iczn ej an alizy to r fó w pcbrainych z różn y ch siedlisk w yk a zały , że system roln iczego u żytk ow a n ia gleb to r fo w y c h m a w yra źn y wrp ły w ma zaw artość w nich o m a w ia n y ch sk ładn ik ów w g lebie oraz na in ten syw n ość w nich m in era li za cji w ęgla i azotu.
Jednak w p ły w użytkowam ia roln iczeg o okazał się w idoczm y szczególn ie w orga n iczn y ch fr a k cja c h gleby.
65 System y upraw rolniczych m iały szczególny w p ły w na wtierzchnie w arstw y g le b y torfow ej, lecz w p ły w ten widoczny był również w~ głębszych w arstw ach p ro fi lów glebow ych. M ineralizacja w ęgla w glebie odbyw ała się intensywniej na ko m binacjach naw ożonych. Naw ożenie m ineralne, a szczególnie nawożenie azotowe»’ zw iększało wydzielanie się C 0 2, natomiast przeważnie zm niejszało m ineralizację azotu w om aw ianych glebach torfowych.
Frof. dr hab. Franciszek Maciak W p ły n ęło do red akcji
K atedra R ek u lty w a cji Środowiska 1985.02.20
Przyrod n iczeg o S G G W -A R
