| Abstrakt: |
Estimates of the effects of mineral fertilizer, manure, and legumes on crop yields and soil fertility in various technologies and environments are important for maintaining efficient crop production and reducing energy use in agriculture. Estimates of these effects were made in a long‐term study (1955 to 1968) at Aurora, N.Y. on soils of the Honeoye‐Lima and Kendaia series (Glossoboric Hapludalf and Aeric Haplaquept; fine loamy, mixed mesics; respectively). The crop sequences included continuous corn (Zea maysL.), wheat (Triticum aestivumL.), and grass and legume forage species, as well as several five‐phase rotations. The management treatments were manure (13.5 metric tons wet weight/ha/year averaged over the crop sequence), no manure, and different rates of N‐P‐K. The phases of each crop sequence were assigned to whole plots (0.0254 ha) in a randomized, complete‐block design (with six blocks or replicates), and the management treatments were assigned to the four sub‐plots. Two years of alfalfa (Medicago sativaL.) apparently contributed 135 kg N/ha to subsequent crops. Manure apparently supplied 5‐1‐4 kg N‐P‐K per metric ton (wet weight). The amounts of N available from manure, alfalfa, and mineral fertilizer were additive, at least on corn. A common N response curve over all cropping systems fit the corn data well, which suggests that manure and crop rotation only affected corn yields through their plant nutrient contributions. Soil organic matter and pH were maintained and extractable soil P and K were increased over the 14 years of the study in both continuous and rotational cropping systems (with or without manure). The results suggest that on these soils, the plant nutrient requirements of field crops can be completely supplied by legumes and manure, by mineral fertilizer, or by some combination of them without leading to decreases in soil fertility. |
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