Sowing

About: Sowing is a research topic. Over the lifetime, 33888 publications have been published within this topic receiving 273438 citations. The topic is also known as: seeding.

The fate of nitrogen from legume and fertilizer sources in soils successively cropped with wheat under field conditions

Abstract: Using 15N-labelled legume material (Medicago littoralis) and fertilizers (urea, (NH4)2SO4, KNO3), a direct comparison has been made of the fate of nitrogen from these sources and their residues, in soils sown with two successive wheat crops. The availability of N from each source to both crops is discussed in terms of the release, movement and immobilization of N in the soil profiles. For fertilizer 15N, uptake by crops, distribution as inorganic 15N in soil profiles, total recovery and percentage recovery in organic residues in soil were not significantly influenced by the form of fertilizer applied. For both legume and fertilizer 15N, uptake by both crops was directly related to input; and uptake by the second crop was directly related to the amounts of 15N residual in soil after the first crop. About 17% of applied legume N was taken up by the tops of the first wheat crop, and, at the time of sowing of the second crop, about 62% remained as organic residues; total recovery in crop and soil averaged 84%. By contrast, about 46% of applied fertilizer N was taken up by crop 1, and at sowing in the following year 29% was present as organic residues, and total recovery in soil plus crop averaged 80% The availabilities of N from both legume and fertilizer residues to a second wheat crop declined markedly but continued to differ significantly (P < 0.01) from each other. Expressed as percentages of total residual 15N present in soils at sowing, the second crop took up about 6% of legume-derived N and about 9% of fertilizer-derived N. Fertilizer N directly contributed 5% and 0.5% respectively of the N of first and second wheat crops, per 10kg of fertilizer N applied ha−1. Under the same conditions, legume N directly contributed about 2% and 1% respectively of the N of successive crops, per 10 kg of legume N applied ha−1. The proportions of grain N derived from the applied sources were higher than those of straw N. For both legume and fertilizer 15N, the amounts of inorganic 15N present in soil profiles at sowing in successive years were directly related to 15N inputs. A small but statistically-significant departure from linearity was observed for inorganic 15N at sowing of crop 2 when related to total recoveries of 15N in soils at that time; the higher the amount of 15N recovered, the greater the proportion present as inorganic 15N in the soil profile. The respective contributions of legume and fertilizer N to the total inorganic N pool in soil at sowing declined each year, but were similar to their contributions to the N of the following wheat crop. Concentrations of inorganic N and 15N in soil profiles varied each year but their patterns of distribution in cropped soils were not influenced by the nature and amount of the initial amendments. The 15N atom% enrichments of the inorganic N at sowing in the cropped soils were relatively uniform throughout the profile.

Soil microbial community, fertility, vegetation and diversity as targets in the restoration management of a meadow grassland

Abstract: 1. The enhancement of biodiversity in meadow grassland, an environmental aim of European agricultural policy, requires definition of appropriate management regimes and the rate at which they enhance biodiversity and change ecosystem properties. We describe vegetation changes in a 10-year trial on mesotrophic grassland that was previously agriculturally improved, plus change in the soil microbial community and fertility, important factors that influence biodiversity. 2. Management treatments were three hay-cut dates, plus two mineral fertilizer, two seed addition and two farmyard manure (FYM) applications. Treatment combinations included the traditional management regime (21 July hay-cut date, no mineral fertilizer, autumn grazing with cattle, spring grazing with sheep), modern variants of this (14 June hay-cut date, mineral fertilizer) and exceptional historic variants (1 September hay-cut date). 3. Sowing seed increased species richness and, in the absence of fertilizer and FYM, produced a plant community similar to Geranium sylvaticum–Anthoxanthum odouratum grassland. The greatest cover of sown species was found in seeded treatments, cut for hay on 21 July, in the absence of mineral fertilizer. The target plant community (MG3b grassland) was most rapidly achieved with a 21 July hay cut. Initial decrease in Ellenberg fertility scores only persisted in the 21 July and 1 September cut dates when mineral fertilizer was absent. Soil phosphate was lowest in the joint absence of mineral fertilizer and FYM. 4. There were few treatment effects on the soil microflora. Bacterial biomass was reduced when FYM was applied with the 14 June cut date, but increased when FYM was applied with the 1 September cut date. Fungal biomass decreased when mineral fertilizer was applied. 5. Increased species richness, primarily through an increase in legumes, stress-tolerant and stress-tolerant ruderal plant strategists, was associated with an increase in soil fungi and the abundance of fungi relative to bacteria. All these were associated with seed addition to unfertilized plots cut on 21 July, in the absence of FYM, indicating a functional role for individual species. 6. Synthesis and applications. The enhancement of biodiversity in meadow grassland is a long-term (> 10-year) secondary succession, most rapidly achieved in the absence of mineral fertilizer by cutting for hay in mid-July and autumn grazing with cattle. The sowing of key functional species, i.e. legumes and Rhinanthus minor, was important in facilitating the staged colonization of other sown species.

A comparison of the effects of micronutrient seed priming and soil fertilization on the mineral nutrition of chickpea (Cicer arietinum), lentil (Lens culinaris), rice (Oryza sativa) and wheat (Triticum aestivum) in Nepal

Abstract: Soil deficiencies of zinc (Zn) and boron (B) limit crop production in Nepal. Improving the micronutrient status of plants would increase yield and increase micronutrient content of the seeds, leading to better nutrition of the progeny crop and to improved human micronutrient nutrition. The primary micronutrient problem in grain legumes is B deficiency, while in rice (Oryza sativa), Zn deficiency is more important, and wheat (Triticum aestivum) suffers from both deficiencies. A series of field experiments was carried out over two seasons to compare soil fertilization and micronutrient seed priming as methods of improving Zn and B nutrition of each crop. Micronutrient treatments were evaluated for their effect on grain yield and grain micronutrient content. Soil B fertilization increased B content of the grain of lentil (Lens culinaris), chickpea (Cicer arietinum), and wheat by a factor of two to five, while increasing the yield of chickpea only. Soil fertilization with Zn had no effect on yield of any crop, but resulted in a small increase in Zn in wheat grain. Sowing micronutrient-primed seeds had no effect on yield or micronutrient content of the progeny seeds in most cases. During the first season, the primed chickpea seeds failed to emerge at either site, causing complete yield loss, but this negative effect was not observed in the second season with similar priming treatments at nearby sites, and no effect of priming on yield was observed with any other crop in either season.