KOMPJUTORSKI MODEL OCJENJIVANJA KVALITETE ORGANSKIH GNOJIVA

Evaluation of manures, composts and growing media quality should include enough properties to enable an optimal use from productivity and environmental points of view. The aim of this paper is to describe basic structure of organic fertilizer (and growing media) evaluation model to present the model example by comparison of different manures as well as example of using plant growth experiment for calculating impact of pH and EC of growing media on lettuce plant growth. The basic structure of the model includes selection of quality indicators, interpretations of indicators value, and integration of interpreted values into new indexes. The first step includes data input and selection of available data as a basic or additional indicators depending on possible use as fertilizer or growing media. The second part of the model uses inputs for calculation of derived quality indicators. The third step integrates values into three new indexes: fertilizer, growing media, and environmental index. All three indexes are calculated on the basis of three different groups of indicators: basic value indicators, additional value indicators and limiting factors. The possible range of indexes values is 0-10, where range 0-3 means low, 3-7 medium and 7-10 high quality. Comparing fresh and composted manures, higher fertilizer and environmental indexes were determined for composted manures, and the highest fertilizer index was determined for composted pig manure (9.6) whereas the lowest for fresh cattle manure (3.2). Composted manures had high environmental index (6.0-10) for conventional agriculture, but some had no value (environmental index = 0) for organic agriculture because of too high zinc, copper or cadmium concentrations. Growing media indexes were determined according to their impact on lettuce growth. Growing media with different pH and EC resulted in very significant impacts on height, dry matter mass and leaf area of lettuce seedlings. The highest lettuce seedlings with highest mass and leaf area are produced using growing media with pH close to 6 and with EC lower than 2 dSm-1. It could be concluded that conductivity approx. 3 dSm-1 has inhibitory effect on lettuce if pH is about 7 or higher. The computer model shows that raising pH and EC resulted in decreasing growth which could be expressed as increasing stress index. The lettuce height as a function of pH and EC is incorporated into the model as stress function showing increase of lettuce height by lowering EC from 4 to 1 dSm-1or pH from 7.4 to 6. The highest growing media index (8.1) was determined for mixture of composted pig manure and peat (1:1), and lowest (2.3) for composted horse manure and peat (1:2.)Ocjena kvalitete organskih gnojiva (stajska gnojiva, komposti) i supstrata treba sadržavati dovoljno informacija da omogući izbor optimalne upotrebe s proizvodnog i ekološkog aspekta. Cilj je ovoga rada prikaz osnovne strukture modela za determinaciju indeksa ocjenjivanja kvalitete organskih gnojiva i supstrata. Osnovna struktura modela sadrži izbor i interpretaciju vrijednosti indikatora kvalitete te integraciju interpretiranih vrijednosti u nove indekse. Prvi korak uključuje unos podataka i izbor raspoloživih podataka za izračun osnovnih ili dopunskih indikatora, ovisno o indeksima i mogućim uporabama kao gnojivo ili supstrat. U drugom koraku raspoloživi podaci koriste se za izračun izvedenih indikatora kvalitete, a treći korak je integracija interpretiranih vrijednosti u tri nova indeksa: fertilizacijski indeks, indeks supstrata i ekološki indeks. Vrijednosti sva tri indeksa računaju se na temelju tri grupe indikatora: indikatori osnovne vrijednosti, indikatori dopunskih vrijednosti i limitirajući faktori. Raspon vrijednosti sva tri indeksa kreće se od 0-10, pri čemu raspon 0-3 znači nisku, 3-7 srednju, a 7-10 visoku kvalitetu. Usporedbom svježih i kompostiranih stajskih gnojiva, viši fertilizacijski i ekološki indeksi utvrđeni su za kompostirana gnojiva, najviši fertilizacijski indeks utvrđen je za kompostirani separat svinjske gnojovke (9,6), a najniži za svježi goveđi stajski gnoj (3,2). Kompostirana stajska gnojiva imaju visoki ekološki indeks (6,0-10) za konvencionalnu poljoprivredu, ali pojedini nemaju ekološku vrijednost (ekološki indeks = 0) za ekološku poljoprivredu zbog visoke koncentracije cinka, bakra ili kadmija. Indeksi supstrata utvrđeni su prema utjecaju supstrata na rast salate. Supstrati s različitim pHH2O i EC vrijednostima rezultirali su vrlo značajnim utjecajem na visinu presadnica salate, produkciju suhe tvari i površinu lista. Najveće presadnice s najvećom masom i lisnom površinom proizvedene su uporabom supstrata s pHH2O vrijednošću oko 6 i EC vrijednošću ispod 2 dSm-1. Može se zaključiti da konduktivitet oko 3 dSm-1 ima inhibitorni učinak na salatu ukoliko je pH supstrata oko 7 ili viši. Kompjutorski je model pokazao da povećanje pHH2O i EC rezultira smanjenim rastom salate, što se može izraziti kao porast stres indeksa. Visina salate kao funkcija pHH2O i EC ugrađena je u model kao stres funkcija koja pokazuje povećanje salate smanjenjem EC vrijednosti od 4 do 1 dSm-1 ili pHH2O vrijednosti od 7,4 do 6. Najveći indeks supstrata (8,1) utvrđen je za smjesu (1:1) kompostiranog separata svinjske gnojovke i treseta, a najniži (2,3) za smjesu (1:2) kompostiranog konjskog stajskog gnojiva i treseta

INFLUENCE OF ORGANIC FERTILIZATION ON YIELD, CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF MAIZE KERNEL

Zbog sve većeg zanimanja za zaštitu okoliša, povećanje plodnosti tla, ali i zbog mogućnosti dodatnog zapošljavanja stanovništva ruralnih područja, na pokušalištu Visokog gospodarskog učilišta u Križevcima, provedeno je istraživanje o mogućnostima proizvodnje stočne hrane na principima ekološke poljoprivrede. Pokus je postavljen po slučajnom bloknom rasporedu u četiri ponavljanja. Veličina parcele svakoga gojidbenog tretmana iznosila je 70 m2, a tretmani su bili: I - kontrola (bez gnojidbe); II - mineralna gnojidba (200 kg ha-1 N, 150 kg ha-1 P2O5 i 300 kg ha-1 K2O); III - 10 t ha-1 komposta od goveđeg gnoja; IV - 10 t ha-1 komposta od konjskog gnoja; V - 10 t ha-1 komposta od separata svinjske gnojovke; VI - 6 t ha-1 komposta od pilećeg gnoja. Istraživanje je provedeno tijekom 2008. s hibridom kukuruza Pioneer PR38A24 FAO skupine 380. Najveći ostvareni prinos (14,95 t ha-1) i najveći sadržaj sirovih proteina (98,28 g kg-1) utvrđeni su kod tretmana II (mineralna gnojidba), dok su prinosi gojidbenih tretmana III – VI, kod kojih su primjenjivana organska gnojiva, manji za 23 – 32%, a sadržaj sirovih proteina za 13 – 36%. Nasuprot tome sadržaj sirovih masti, ME i NEL-a po kg suhe tvari najmanji su kod tretmana II (mineralna gnojidba), a značajno veći kod tretmana gdje su korištena organska gnojiva različitog podrijetla. Analizom varijance utvrđeno je da između svih prosječnih analitičkih parametara postoje statistički značajne razlike na 5%-tnoj razini (P<0,05), dok su razlike na 1%-tnoj razini (P<0,01) utvrđene kod ostvarenoga prinosa i sadržaja sirovoga proteina te NEL-a. Za zaključiti je da se u ekološkoj proizvodnji i gnojidbom samo organskim gnojivima, neovisno o njihovom podrijetlu, postižu nešto niži prinosi po jedinici površine, međutim zbog pozitivnog učinka organske tvari u tlu, koristi će biti puno veće.Following the increased interest in environment protection and increase in the soil fertility, as well as the possibility for additional employment of the inhabitants in the rural area, a research into the possibilities to produce animal feedstuffs was conducted on the experimental field of the College of Agriculture at Križevci. The experiment was set in a randomized block scheme with four repetitions. The size of the plot for each fertilization treatment was 70 sq m. The treatments were the following: I-control (no fertilization), II- mineral fertilizers (200 kg ha-1 N, 150 kg ha-1 P2O5 and 300 kg ha-1 K2O), III – 10 t ha-1 cow manure compost, VI - 10 t ha-1 horse manure compost; V - 10 t ha-1 composted pig slurry, VI – 6 t ha-1 composted poultry manure. The experiment was conducted in 2008 using the maize hybrid Pioneer PR38A24 FAO group 380. The highest yield (14.95 t ha-1) and the highest raw protein content (98.28 g kg-1) were determined for treatment II (mineral fertilizers), while the yield with treatments III-VI, in which organic fertilizers were used, was 23 to 32% lower, and the protein content was 13-36% lower. Contrary to that, the crude fats, ME and NEL content per kg of the dry matter was lowest for treatment II (mineral fertilization) and significantly higher in treatments where variations of organic fertilizers were used. The analysis of variance showed statistically significant differences between all average analytical parameters at the level of 5 per cent (P<0.05), while the differences at the level of 1 percent (P<0.01) were determined for the yield, crude protein content and NEL. It can be concluded that the ecological production and fertilization with only organic fertilizers, regardless of their origin, produce lower yield per surface area. However, due to the positive effect of the organic matter in the soil, the benefits are much higher

INFLUENCE OF FERTILIZATION ON YIELD, CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF MAIZE COB AND GRAIN

Radi utvrđivanja optimalne gnojidbe i njezinog utjecaja na kemijski sastav i hranidbenu vrijednost klipa i zrna kukuruza (OSSK 444), vršena su ispitivanja tijekom tri godine (2004.-2006.) na površinama ekonomije Visokog gospodarskog učilišta u Križevcima. Pokus je postavljen po slučajnom blok rasporedu u četiri ponavljanja. Veličina parcele svakoga tretmana je bila 70 m2 (7x10 m), a tretmani su bili: 1 - bez gnojidbe; 2 - N80P100K0; 3 - N80P0K100; 4 - N0P100K100; 5 - N80P100K100; 6 -N120P100K100; 7 - N120P200K200; 8 - N160P200K200; 9 - N200P200K200; 10 -N240P200K200. Analizom tla utvrđena je blago kisela reakcija (pHKCl = 5,93), nizak sadržaj humusa (1,99%), te osrednja opskrbljenost fosforom i kalijem (135,00 i 157,00 mg/kg). Analiza klipa i zrna kukuruza obavljena je metodom po Weendeu, a na osnovi utvrđenih sirovih organskih hranjivih tvari i pepela u suhoj tvari, izračunata je metabolička energija (ME) i neto energija za laktaciju (NEL). Rezultati istraživanja su pokazali da postoji značajan utjecaj gnojidbe na sadržaj sirovoga proteina u klipu (91,99 - 108,35 g/kg) i zrnu (109,48 - 128,72 g/kg), dok je utjecaj gnojidbe na sadržaj sirove vlaknine utvrđen samo u klipu kod pojedinih gnojidbenih tretmana (P0,05).In order to establish the most appropriate treatment, an analysis of the influence of various fertilization treatments on chemical compound of maize cob and grain (OSSK 444) was made on the college farm in Križevci in a three-year period (2004-2006). The experimental trial was organized in four repetitions and in a randomized block scheme. The size of the plot for each treatment was 70 square meters (7x10 m), and the treatments were as follows: 1 – no fertilization; 2 - N80P100K0; 3 - N80P0K100; 4 - N0P100K100; 5 - N80P100K100; 6 -N120P100K100; 7 - N120P200K200; 8 - N160P200K200; 9 - N200P200K200; 10 -N240P200K200. The soil analysis established a mild acid reaction (pH in KCL = 5.93), low humus content (1.99%) and medium supply level of phosphorus and potassium (135 and 157 mg/kg). The analyses of the maize grain and cob were made according to Weende. The metabolic energy (ME) and net energy for lactation (NEL) were calculated on the basis of the determined crude organic nutrients and crude ash in maize grain and cob dry matter. The results of this research lead to the conclusion that the fertilization influences the crude protein content in maize cob (91.99 – 108.35 g/kg) and grain (109.48 and 128.72 g/kg), while only certain fertilization treatments influence the crude fibre content in maize cob (P<0,05). However, fertilization does not significantly influence the average crude oil content, crude NET and the nutritive value of maize cob and grain (ME and NEL)

MODIFICATIONS OF CHEMICAL PROPERTIES OF MANURE IN THE PROCESS OF COMPOSTING

Suvremena poljoprivredna proizvodnja, pored proizvodnje dostatne količine hrane, mora proizvoditi visokokvalitetnu hranu, ali i očuvati okoliš, prvenstveno očuvanjem tala, kao prirodnog i obnovljivog, ali iscrpljivoga resursa. Očuvanje tala izravno naglašava brigu o osnovnim svojstvima tla koja utječu na njegovu plodnost, a jedna od mjera je primjena organskih gnojiva. U praksi se najčešće koristi stajski gnoj, a procesi razgradnje, koji, ovisno o načinu držanja stoke i izgnojavanja te uvjeta u kojima se takva masa skuplja i drži, često ne idu u željenome smjeru i prilikom primjene takvoga gnoja izostaju očekivani pozitivni učinci, a nerijetko se javljaju i negativni. U pokusu je kompostirano pet različitih stajskih gnojiva (svježi i poluzreli goveđi, konjski, svinjski i pileći) i praćene su promjene kemijskih svojstava. Tijekom procesa kompostiranja došlo je do značajnih promjena: pH reakcija početnih kompostnih materijala narasla je kod svih komposta (od 8 na iznad 9), osim svinjskoga, čija je pH vrijednost bila ispod 7; EC se povećao prosječno za 69%, na kraju istraživanja utvrđen je vrlo visok EC u pilećem (12,15 d•Sm-1, što je trostruko iznad graničnih vrijednosti za supstrat za kontejnersku proizvodnju) i konjskom (8,75 d•Sm-1, što je gotovo dvostruko iznad tih vrijednosti). Čitav proces kompostiranja karakterizira opadanje udjela organskoga C (prosječno za 19,62%), dok je suprotna dinamika udjela ukupnoga N (prosječni porast za 38%). C•N odnos se u kompostima očekivano smanjio ispod 20:1, uz najveći pad kod goveđih stajskih gnojiva s najvišim početnim C•N odnosom. Utvrđen je i porast nitratnog oblika dušika, uz pad udjela amonijačnog.Apart from the production of sufficient food quantities modern agricultural production should produce high- quality food, but also preserve the environment, primarily by preserving the soil as a natural, renewable, but also exhaustible resource. Preservation of soil directly emphasizes the concern about elementary properties of soil affecting its fertility. One of the measures is usage of organic manure. Manure is used most often in practice, and the processes of decomposition depending on the way of maintenance and manure removal of the cattle, and the conditions in which such stack is amassed and kept are not often desirably directed. During implementation of such manure, the expected positive effects appear to be the negative ones. Five different manure types have been composted in the experiment (cattle manure, horse, pig and poultry) and the changes in the chemical properties have been monitored. During the process of composting significant changes have occured: pH level of initial compost materials has grown in all the composts (from 8 to over 9), except for the pig, which had the pH level below 7; EC had an average increase of 69%, and at the end of the research a very high EC was found out in the poultry (12.15 d•Sm-1 which is three times above the borderline values for substrates of container production) and horse (8.75 d•Sm-1 which is almost twice the value). The entire process of composting is characterized by the decrease of the portion of organic carbon (on the average for 19.62%), while the dynamics of the portion of the total N is vice versa (average increase by 38%). C•N ratio in the composts decreased, as expected, below 20:1 and the highest decrease is with the cattle manure with the highest initial C•N ratio. The increase of NO3- and decrease of NH4+ were established

COMPUTER MODEL FOR ORGANIC FERTILIZER EVALUATION

Evaluation of manures, composts and growing media quality should include enough properties to enable an optimal use from productivity and environmental points of view. The aim of this paper is to describe basic structure of organic fertilizer (and growing media) evaluation model to present the model example by comparison of different manures as well as example of using plant growth experiment for calculating impact of pH and EC of growing media on lettuce plant growth. The basic structure of the model includes selection of quality indicators, interpretations of indicators value, and integration of interpreted values into new indexes. The first step includes data input and selection of available data as a basic or additional indicators depending on possible use as fertilizer or growing media. The second part of the model uses inputs for calculation of derived quality indicators. The third step integrates values into three new indexes: fertilizer, growing media, and environmental index. All three indexes are calculated on the basis of three different groups of indicators: basic value indicators, additional value indicators and limiting factors. The possible range of indexes values is 0-10, where range 0-3 means low, 3-7 medium and 7-10 high quality. Comparing fresh and composted manures, higher fertilizer and environmental indexes were determined for composted manures, and the highest fertilizer index was determined for composted pig manure (9.6) whereas the lowest for fresh cattle manure (3.2). Composted manures had high environmental index (6.0-10) for conventional agriculture, but some had no value (environmental index = 0) for organic agriculture because of too high zinc, copper or cadmium concentrations. Growing media indexes were determined according to their impact on lettuce growth. Growing media with different pH and EC resulted in very significant impacts on height, dry matter mass and leaf area of lettuce seedlings. The highest lettuce seedlings with highest mass and leaf area are produced using growing media with pH close to 6 and with EC lower than 2 dSm-1. It could be concluded that conductivity approx. 3 dSm-1 has inhibitory effect on lettuce if pH is about 7 or higher. The computer model shows that raising pH and EC resulted in decreasing growth which could be expressed as increasing stress index. The lettuce height as a function of pH and EC is incorporated into the model as stress function showing increase of lettuce height by lowering EC from 4 to 1 dSm-1or pH from 7.4 to 6. The highest growing media index (8.1) was determined for mixture of composted pig manure and peat (1:1), and lowest (2.3) for composted horse manure and peat (1:2.