Thirty years of growing cereal without P and K fertilization

Over thirty years a significant depletion of P and K in soil occured when the were not given in fertilizers. This caused a reduction in crop yield. An abundant P application exceeding the crop uptake very clearly prevented the yield reduction but did not raise the extractable P concentration in the soil. Severe K deficiency did not start to appear until 20 years of growing cereal without fertilizer K. K application compensating for the uptake by the crop did not prevent the decrease of its extractable concentration in this soil, but this decrease did not affect crop yield

Olkien, olkituhkan ja sokerijuurikkaan naattien arvo kaliumlannoitteina

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Viljelykasvin vaikutus ravinteiden huuhtoutumiseen savimaasta Jokioisten huuhtoutumiskentällä v. 1983-1986

VokKirjasto Aj-

Viljelykasvin ja lannoituksen vaikutus ravinteiden huuhtoutumiseen turvemaasta Tohmajärven huuhtoutumiskentällä v. 1983-87

vKirjasto Aj-

Viljelykasvin ja lannoitustason vaikutus typen ja fosforin huuhtoutumiseen savimaasta

vokKirjasto Aj-

Viljelykasvin, lannoituksen ja sadetuksen vaikutus kaliumin, kalsiumin , magnesiumin, natriumin, sulfaattirikin sekä kloridin huuhtoutumiseen savimaasta

vokKirjasto Aj-

First-order logic with self-reference

We consider an extension of first-order logic with a recursion operator that corresponds to allowing formulas to refer to themselves. We investigate the obtained language under two different systems of semantics, thereby obtaining two closely related but different logics. We provide a natural deduction system that is complete for validities for both of these logics, and we also investigate a range of related basic decision problems. For example, the validity problems of the two-variable fragments of the logics are shown coNexpTime-complete, which is in stark contrast with the high undecidability of two-variable logic extended with least fixed points. We also argue for the naturalness and benefits of the investigated approach to recursion and self-reference by, for example, relating the new logics to Lindstrom's Second Theorem

Complexity Classifications via Algebraic Logic

Complexity and decidability of logics is an active research area involving a wide range of different logical systems. We introduce an algebraic approach to complexity classifications of computational logics. Our base system GRA, or general relation algebra, is equiexpressive with first-order logic FO. It resembles cylindric algebra but employs a finite signature with only seven different operators, thus also giving a very succinct characterization of the expressive capacities of first-order logic. We provide a comprehensive classification of the decidability and complexity of the systems obtained by limiting the allowed sets of operators of GRA. We also discuss variants and extensions of GRA, and we provide algebraic characterizations of a range of well-known decidable logics

Algebraic classifications for fragments of first-order logic and beyond

Complexity and decidability of logics is a major research area involving a huge range of different logical systems. This calls for a unified and systematic approach for the field. We introduce a research program based on an algebraic approach to complexity classifications of fragments of first-order logic (FO) and beyond. Our base system GRA, or general relation algebra, is equiexpressive with FO. It resembles cylindric algebra but employs a finite signature with only seven different operators. We provide a comprehensive classification of the decidability and complexity of the systems obtained by limiting the allowed sets of operators. We also give algebraic characterizations of the best known decidable fragments of FO. Furthermore, to move beyond FO, we introduce the notion of a generalized operator and briefly study related systems.Comment: Significantly updates the first version. The principal set of operations change

Peltomaiden kalkitustarve ja kalkituksen vaikutus viljan ja nurmen satoon

vokKirjasto Aj-kEffect of liming on yield of cereals and gras