Drought and salinity: A comparison of their effects on mineral nutrition of plants

The increasing frequency of dry periods in many regions of the world and the problems associated with salinity in irrigated areas frequently result in the consecutive occurrence of drought and salinity on cultivated land. Currently, 50% of all irrigation schemes are affected by salinity. Nutrient disturbances under both drought and salinity reduce plant growth by affecting the availability, transport, and partitioning of nutrients. However, drought and salinity can differentially affect the mineral nutrition of plants. Salinity may cause nutrient deficiencies or imbalances, due to the competition of Na⁺ and Cl^– with nutrients such as K⁺, Ca²⁺, and NO . Drought, on the other hand, can affect nutrient uptake and impair acropetal translocation of some nutrients. Despite contradictory reports on the effects of nutrient supply on plant growth under saline or drought conditions, it is generally accepted that an increased nutrient supply will not improve plant growth when the nutrient is already present in sufficient amounts in the soil and when the drought or salt stress is severe. A better understanding of the role of mineral nutrients in plant resistance to drought and salinity will contribute to an improved fertilizer management in arid and semi‐arid areas and in regions suffering from temporary drought. This paper reviews the current state of knowledge on plant nutrition under drought and salinity conditions. Specific topics include: (1) the effects of drought and salt stress on nutrient availability, uptake, transport, and accumulation in plants, (2) the interactions between nutrient supply and drought‐ or salt‐stress response, and (3) means to increase nutrient availability under drought and salinity by breeding and molecular approaches.     

Effect of Harvest Timing on Yield and Mineral Nutritional Value of Kabuli Type Chickpea Seeds

Chickpea (Cicer arietinum L.) seeds are a good source of protein and mineral nutrients. However, there is no information regarding harvest timing on yield and mineral composition of chickpea seeds. The effect of harvest timing on seed yield, some yield components and mineral nutritional value of seeds of field grown chickpea plants in two different sites were studied. The mineral composition of chickpea straw depending on harvest timing was also evaluated in order to explain the variations of seed mineral concentrations in sink-source relationship manner. Yield and mineral nutritional value of chickpea were significantly affected by harvest timing. When compared to the seed yield at optimal harvest time, seed yield was 18% and 9% lower in the early harvest and 27% and 31% in the late harvest in Site 1 and Site 2, respectively. Late harvest of chickpea crops resulted in significant pod dropping and shattering. Generally, protein, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and manganese (Mn) concentrations of the seeds in optimal harvest were found to be greater than in early and late harvested plants. Harvest timing also results in significant variations in straw mineral nutrient concentrations of the plants. As the results of this study, it was concluded that the harvest timing is critical for yield losses and mineral nutritional value of chickpea seeds.     

Nitrogen Fractions in Arable Soils in Relation to Nitrogen Mineralization and Plant Uptake

Abstract

Nitrogen (N) as a major constituent of all plants is one of the most important nutrients. Minimizing input of mineral nitrogen fertilizer is needed to avoid harm to the environment. Optimal input of mineral nitrogen should take the nitrogen supply of the soil into account. Many different soil tests have been proposed for determining soil nitrogen availability. In this article we present a new approach that is based on the measurement of nitrate, ammonium, and dissolved organic nitrogen (DON) in a 0.01 M CaCl₂ soil extract. Eighteen agricultural soils, differing widely in the availability of nitrogen were used, fertilized and unfertilized. It is shown that the nitrogen uptake by maize plants (Zea Mays L.) in both “N‐fertilized” and “N‐unfertilized” soils as measured in a pot experiment can be described with a simple model using the measured nitrogen fractions in the extract. The main source of nitrogen uptake by the plants is the mineralized organic nitrogen during the growing period. It is shown that the initial measured DON fraction is a good indicator of the nitrogen mineralized during plant growth.     

Changes in mineral nutrient concentrations and C‐N metabolism in cabbage shoots and roots following macronutrient deficiency

The responses of metabolic networks to mineral deficiency are poorly understood. Here, we conducted a detailed, broad‐scale analysis of macronutrient concentrations and metabolic changes in the shoots and roots of cabbage (Brassica rapa L. ssp. pekinensis) plants in response to N, P, K, Ca, and Mg deficiency in nutrient solution. To standardize individual macronutrient‐deficient treatments, the concentrations of the other nutrients were maintained via substitution with other ions. Individual nutrient deficiencies had various effects on the uptake and accumulation of other mineral nutrients. Phosphorus deficiency had relatively little effect on other mineral nutrient levels compared to the other treatments. Cation deficiency had little effect on N and P concentrations but had a somewhat negative effect on the uptake or concentrations of the other nutrients. Primary metabolic pathways, such as energy production and amino acid metabolism, were greatly affected by mineral nutrient deficiency. Compared to the control treatment, soluble sugar levels increased under –N conditions and decreased under –Ca and –Mg conditions. The levels of several organic acids involved in glycolysis and the TCA cycle decreased in response to –N, –P, or –K treatment. The levels of most amino acids decreased under ‐ N treatment but increased under –P, –K, –Ca, or –Mg treatment. Mineral depletion also led to the activation of alternative biochemical pathways resulting in the production of secondary metabolites such as quinate. Notable changes in metabolic pathways under macronutrient deficiency included (1) a quantitative increase in amino acid levels in response to Mg deficiency, likely because the restriction of various pathways led to an increase in protein production and (2) a marked increase in the levels of quinate, a precursor of the shikimate pathway, following cation (K, Ca, and Mg) deficiency. These findings provide new insights into metabolic changes in cabbage in response to mineral deficiency and pave the way for studying the effects of the simultaneous deficiency of more than one macronutrient on this crop.     

Effects of weathering state of coarse‐soil fragments on tree‐seedling nutrient uptake

Fine earth accumulated within the weathering fissures of the coarse‐soil fraction (particles > 2 mm), so called “stone‐protected fine earth”, can provide a high short‐term nutrient release by cation exchange. It is thus hypothesized that unweathered gneiss particles cannot provide plants with exchangeable‐cation nutrients and that biological weathering is needed to include silicate‐bound nutrients into biochemical cycles. In a microcosm experiment, ectomycorrhizal Norway spruce (Picea abies) seedlings were grown on either weathered or unweathered paragneiss coarse‐soil fragments under natural hydraulic and climatic boundary conditions. A nutrient solution containing N, P, and K was added, however Mg and Ca could only be taken up from the coarse‐soil substrate. Solutes in drainage were analyzed during the experiment; plant nutrient uptake was determined after the experiment ended. Solute dynamics depended on the weathering state of the substrates: unweathered gneiss showed high initial Mg and Ca fluxes that diminished strongly afterwards, whereas weathered gneiss showed a much more gradual and sustainable release of these cations. Patterns in dissolved organic C and sulfate drainage indicated that the internal pores of weathered gneiss fragments contained organic material most likely as a result of living spaces from microorganisms. Plant biomass did not differ between treatments, however Mg content was higher in seedlings grown on weathered gneiss. Nutrient budgets demonstrated that the “stonesphere” of weathered gneiss can act as a quasi‐constant nutrient source whereas unweathered gneiss only provided high initial nutrients fluxes. In nutrient‐depleted, acidified fine‐earth environments, the coarse‐soil fraction may therefore act as a retreat for nutrient‐adsorbing tissues and as a buffer for nutrient shortages.     

Potassium and calcium distribution patterns along the leaf insertion gradient of bean plants grown in nutrient solutions

Potassium and calcium distribution patterns along the leaf insertion gradient of bean plants (Phaseolus vulgaris L. cv Tacarigua) were analyzed in plants grown in different K and Ca concentrations in the nutrient solution. The plants were sampled at the early flowering stage and the leaves analyzed following the helix or genetic spiral which follows leaves in the order of their origin at the shoot tip. Different canopy profiles for K and Ca showed that “critical concentration limits”; could be established for K but not for Ca, due perhaps to the non‐phloem mobile nature of this element. Besides, sampling procedures based on a “representative”; leaf (or leaves) were compared to those based on the sampling of the whole canopy in order to obtain reference nutrient concentration values.     

The Effect of the Ionic Strength of Nutrient Solution on Gas Exchange,Ionic Concentration and Leaf Biomass of Annona emarginata (Schltdl.) H. Rainer Variety ‘Terra-Fria’ Seedlings

The present study aimed to test the hypothesis that different levels of the availability of mineral nutrients from Hoagland and Arnon's nutrient solution no. 2 affect the photosynthesis, ionic concentration and biomass production in seedlings of Annona emarginata (Schltdl.) H. Rainer variety ‘terra-fria’. Seedlings were grown in a hydroponic setting with 100% ionic strength and with ionic strength reduced to 75%, 50%, and 25%. Ionic strengths intermediate resulted in higher rates of carbon net assimilation and plants grown under these conditions increased biomass as well ionic concentrations of calcium, magnesium and sulfur. The ‘terra-fria’ plants with nutrient solutions of 50% and 75% ionic strength exhibited higher ionic concentrations, instantaneous carboxylation efficiency and biomass production. It can be concluded that the ‘terra-fria’ does not require the maximum mineral nutrients availability from Hoagland and Arnon's nutrient solution to achieve high primary productivity and intermediate ionic strengths can even reduce the time required for rootstock formation.     

Influence of shade on mineral nutrient status of field‐grown cotton

Photosynthetic irradiance has variable effects on cotton (Gossypium hirsutum L.) growth, development, lint yield and fiber quality. However, little is known about the effect of shade on the mineral nutrient status of cotton plants. A two‐year study was conducted to determine the effects of shade (63% light reduction) at different growth stages on mineral nutrient concentrations in plant components of field‐grown cotton. Averaged over the three growth stages of first flower, peak flower, and boll development, an 8‐day period of shade increased petiole NO₃‐N, phosphorus (P), potassium (K), and sulfur (S) concentrations by 145, 17, 20, and 18%, respectively. Total nitrogen (N), P, K, S, calcium (Ca), and magnesium (Mg) concentrations in the leaf blades of the sampled petioles increased 19, 29, 22, 22, 13, and 16%, respectively, compared with those of unshaded control plants. However, bracts and floral buds of 20‐day‐old squares of shaded cotton plants showed a slight decrease (6%) in total N concentration, and increases in the other mineral nutrient concentrations. The increased mineral nutrients of shaded plants were closely associated with decreased carbohydrate accumulation. Shade during plant reproductive growth significantly affected nutrient status and TNC/N ratio of cotton. This study indicated that light intensity at the time of sampling can cause non‐representative nutrient analysis and erroneous diagnostic recommendations. Therefore, the time of day and light conditions must be considered when sampling cotton petioles and other tissues for nutrient diagnoses.     

Yields nutrient intake and soil fertilizing in 40 years fertilizer trials

The set of twenty long‐term field nutrition trials starting from 1957 at five sites. The sites differed by their altitude (from 180 m to 620 m) with average daily temperatures (from 6,8°C m to 9°C m) and soil type (from chernozem to brown podsolic soil) Provided mainly the following results:

? The geonomic division to the fertile sugarbeet region and less fertile potato region did not strictly differentiate the influence of fertilizer and climatic effects to the crop yields.

? The effect of fertilizing was dependent on the nutrient content and on the conditions of releasing and binding of the nutrients in soil.

? The precipitation regime has a strong influence on the effect of the nitrogen escalated doses.

? The facts concerning the nutrient intake are very precious knowledge. These facts have not been examined yet during the long‐term trials.

? The site effect, particularly its climatic conditions, on the nutrient intake is often more obvious compared to the fertilizing effect.

? Very interesting impulses for further research monitoring during the long‐term trials was contributed by “mapping”; of soil capacity to provide nutrients to plants at various sites and under different climate.     

Dry‐matter production,mineral nutrient concentrations,and nutrient distribution and redistribution in irrigated spring wheat

A field study was made of the seasonal changes in dry‐matter production, and the uptake, distribution, and redistribution of 12 mineral nutrients in the semi‐dwarf spring wheat, Egret, grown under typical irrigation farming conditions. Most of the dry‐matter production and nutrient uptake had occurred by anthesis, with 75–100% of the final content of magnesium (Mg), copper (Cu), chloride (Cl), sulfur (S), phosphorus (P), nitrogen (N), and potassium (K) being taken up in the pre‐anthesis period. The above‐ground dry‐matter harvest index was 37%, and grain made up 76% of the head dry matter. Redistributed dry matter from stems and leaves could have provided 29% of the grain dry matter. Concentrations of phloemmobile nutrients, such as N and P, decreased in the leaves and stems throughout the season, whereas concentrations of phloem‐immobile nutrients, such as calcium (Ca) and iron (Fe), generally increased. The decline in the N concentration in stems and leaves was not prevented by N fertilizer applied just before anthesis. Leaves had the major proportion of most nutrients in young plants, but stems had the major proportion of these nutrients at anthesis. Grain had over 70% of the N and P, and 31–64% of the Mg, manganese (Mn), S, and zinc (Zn), but less than 20% of the K, Ca, sodium (Na), Cl, and Fe in the plant. Over 70% of the N and P, and from 15 to 51% of the Mg, K, Cu, S, and Zn was apparently redistributed from stems and leaves to developing grain. There was negligible redistribution of Ca, Na, Cl, Fe, and Mn from vegetative organs. Redistribution from stems and leaves could have provided 100% of the K, 68–72% of the N and P, and 33–48% of the Zn, Cu, Mg, and S accumulated by grain. It was concluded that the distribution patterns of some key nutrients such as N, P, and K have not changed much in the transition from tall to semi‐dwarf wheats, and that the capacity of wheat to redistribute dry matter and nutrients to grain is a valuable trait when nutrient uptake is severely restricted in the post‐anthesis period.     

根际动态过程与植物营养

养分的有效性是由土壤物理、化学和生物学特性,特别是根系主导的根际动态过程所决定的。根系引起根际pH值和氧化还原电位、根分泌物以及由此引起微生物种群、数量和活性的改变,从根本上决定着根际养分的动态。而根系主导的根际动态又具有明显的基因型差异,并受植物营养状况的诱导和调控。因此,根际动态变化的方向和强度对植物适应土壤化学和物理逆境具有重要意义。本文从根际的一般概念入手,综述了近十余年来国内外根际动态研究的新成果,重点讨论了根际动态与植物营养的关系,并运用根际微生态系统的概念,把根际动态与植物对养分胁迫的适应性及其调控机理紧密联系起来,使根际动态和植物矿质营养基因型差异机理两个基础性研究热点融为一体,为解决重大的全球性环境、生态以及农业持续发展问题提供新的途径和理论依据。     

Nutrient uptake,partitioning, and removal in two modern high-yielding Colombian rice genotypes

Abstract

The objective of this research was to determine the difference on growth between a rice cultivar with Clearfield^® technology (Only Rice 228) and a hybrid (Benja 1); to characterize nutrient uptake, distribution, accumulation and removal between these two commercial genotypes. Tests under shade house and field conditions were performed to estimate macro and micronutrient uptake patterns. Plants were sampled at nine growth stages (emergence, initiation of tillering, active tillering, initiation of panicle primordia, booting, flowering, milky, soft dough and mature grain) and divided into different organs for nutrient determination. The results showed that “Benja 1” plants (92 d) had a shorter cycle than “Only Rice 228” (OR 228) plants (118 d). “OR 228” exhibited a greater biomass production (16.575?kg ha^?1 vs. 12.621?kg ha^?1) in field. The nutrient acquisition was faster in the hybrid Benja 1 between tillering initiation and the milky grain stage in which the N, K, Ca, Mg, Mn, B, and Cu uptake was more evenly and highly distributed throughout these stages in both conditions. “Benja 1” showed a higher nutrient harvest index (HI). HI values above 50% (P (62%), N (61%), Cu (67%), S (55%), and Mg (52%)) were found in Benja 1 under field conditions. The results also highlight Si removal in both rice genotypes, in which Benja 1 stands out. These results provide information on the nutrient uptake and partitioning of modern rice genotypes, and give the knowledge to optimize fertilizer programs and timing recommendations for rice biomass and grain production in Colombia.     

Mineral nutrient concentration and uptake by tomato irrigated with recirculating aquaculture water as influenced by quantity of fish waste products supplied

Fish and tomato (Lycopersicon esculentum Mill.) production were linked in a recirculaing water system. Fish (tilapia) were fed a commercial diet with 32% protein. Tomato cultivars ‘Laura’ and ‘Kewalo’ were grown during summer 1988 and spring 1989, respectively, in a Raleigh, NC greenhouse. Plants were grown in biofilters at 4 plants/m² and surface irrigated 8 times daily with water pumped from an associated fish tank. Four tank‐to‐biofllter ratios were established by varying the filter size. Each system received identical nutrient inputs and an equal quantity of water was applied per plant. Biofilter drainage returned to the tanks. Biological filtration, aeration, and mineral assimilation by plants maintained water quality within limits for tilapia. All nutrients were assimilated above deficiency levels. Tissue concentrations of N, P, K and Mg were not limiting. Calcium was low and S high when their sole nutrient source was fish waste. Micronutrients were assimilated in excess of sufficiency, but toxicity was not seen. Irrespective of fruit yield, metabolic products of each kilogram increase in fish biomass provided sufficient nutrient for two tomato plants for a period of three months. Under reduced growth rates of mature fish, K became limiting. Alterations in fish feed mineral nutrient content are suggested which better meet plant requirements and still remain within the range of fish needs.     

Seedball‐induced changes of root growth and physico‐chemical properties—a case study with pearl millet

Seedball is a cheap “seed‐pelleting‐technique” that combines local materials, seeds and optionally additives such as mineral fertilizer to enhance pearl millet (Pennisetum glaucum (L.) R. Brown) early growth under poor soil conditions. The major objective here was to study the mechanisms behind positive seedball effects. Chemical effects in the rhizosphere and early root development of seedball‐derived pearl millet seedlings were monitored using micro‐suction‐cups to extract soil solutions and X‐ray tomography to visualize early root growth. Pearl millet (single seedling) was grown in soil columns in a sandy soil substrate. Root and shoot biomass were sampled. X‐ray tomography imaging revealed intense development of fine roots within the nutrient‐amended seedball. Seedball and seedball+NPK treatments, respectively, were 65% and 165% higher in shoot fresh weight, and 108% and 227% higher in shoot dry matter than the control treatment. Seedball+NPK seedlings showed promoted root growth in the upper compartment and 105% and 30% increments in root fresh and dry weights. Soil solution concentrations indicate that fine root growth ass stimulated by release of nutrients from the seedballs to their direct proximity. Under real field conditions, the higher root length density and finer roots could improve seedlings survival under early drought conditions due to better ability to extract water and nutrients from a greater soil volume.     

Diagnostic techniques for cereals based on plant analysis II. Diagnosis and yield prognosis models

Abstract

In a relationship between the grain yields and concentrations of a nutrient element at a well defined stage of development under varying growing conditions, i.e. 2.0 g Dry Matter weight (DMw) per hill, the boundary line concept dictates that the grain yield corresponding to the points along the boundary of data points is predominantly determined by the varying concentrations of the respective nutrient element. These concentrations, defined as “Pure‐effect Concentrations,”; form the bases to develop the pure‐effect yield curves. Pure‐effect yield curves were developed for N, P, K, Ca, Mg and Na. The absolutely optimal concentrations or absolute reference values, i.e. the concentrations of various nutrient elements at 2.0 g DMw level corresponding to maximum grain yield, were found to be 3.3% N, 0.36% P, 3.9% K, 1.3% Ca, 0.25% Mg and 0.03% Na.

The relationships were developed between the concentrations of other nutrient elements corresponding to pure‐effect concentrations of a nutrient element in question in all combinations by treating each nutrient element as pure‐effect nutrient at a time. These relationships enable one to determine the varying optimal concentrations of other nutrient elements corresponding to the concentrations of the pure‐effect nutrient. These concentrations are defined as “Relatively Optimal Concentrations”; or “Relative Reference Values.”;

The absolute and relative reference values are the bases for developing the diagnosis and yield prognosis models which can be used to evaluate the nutritional status of lowland rice plants and to predict the grain yield based on the elemental composition of plants at 2.0 g DMw per hill. The procedure for the application of diagnosis and yield prognosis models is demonstrated. A very good agreement was found between the grain yield predicted by using these models and the actual yields, thus indicating a high degree of accuracy in predicting the grain yield.     

Sorghum genotype differences to leaf “red‐speckling”; induced by phosphorus 1

Sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solutions, sand, and soil under greenhouse or growth chamber conditions developed a lower leaf “red‐speckling”; which was induced by phosphorus (P). As P in solution increased, the intensity of the “red‐speckling”; increased. Although the severity of “red‐speckling”; was not directly related to leaf P concentration, leaves with more severe symptoms had higher P concentrations. KS35, ‘Martin’, and ‘Plainsman’ developed severe symptoms, CK60‐Korgi, SC369–3‐1JB, and TX415 developed intermediate symptoms, and NB9040 developed no symptoms when grown at relatively low levels of P (10 to 20 umol per plant). Organic sources of P induced more severe “red‐speckling”; than inorganic sources. The severity of “red‐speckling”; induced by P compounds followed the sequence of gyceryl > ethyl ammonium = phenyl > potassium dihydrogen > calcium meta > calcium dibasic > calcium tribasic > ferric > calcium pyro = ferrous = aluminum phosphates. “Red‐speckling”; on young sorghum leaves may be caused by excess P. This excess or toxic P “red‐speckling”; occurred at P levels lower than had normally been considered or expected.     

Log yard fines as a soil amendment: Pot and field studies

Abstract

This study evaluated the application of high levels of log yard fines (LYF), produced by the screening of log yard residues, as a soil amendment/additive. In both pot and field studies, plant growth decreased as LYF application rate increased. LYF immobilized nitrogen (N) and reduced its availability to plants. In the pot study, both alfalfa (Medicago sativa) and orchard grass (Dactylis glomerota L.) had low yields at the first harvest but much higher yields at the second harvest, indicating that N immobilization decreased with time. Alfalfa growth was superior to orchard grass in the LYF‐amended pot soil due to its ability to fix N. LYF provided mineral nutrients and organic matter, lowered soil density, and also improved soil moisture retention properties. This study suggested that LYF could be used as a N‐immobilizing mulch or as a soil amendment/additive for marginal farmland when fertilized adequately and allowed to stabilize in the soil.     

Vermicompost from municipal sewage sludge affects growth and mineral nutrition of winter rye (Secale cereale) plants

The aim of the study was to investigate sewage sludge vermicompost application effects on growth and mineral nutrition of winter rye (Secale cereale L.) plants as compared to two initial levels of mineral nutrient availability, pure sand and sand enriched with inorganic nutrients at the optimal level. Addition of sewage sludge vermicompost significantly inhibited rye seed germination at 20 to 50% sand substitution independently on mineral nutrient supplement. Growth inhibition was evident at early stages of plant development. However, at the later stages, sewage sludge vermicompost acted both as mineral fertilizer and plant growth-promoting agent. Significant stimulation of mineral uptake was seen only at high rates of vermicompost substitution (40 and 50%) already causing decrease in shoot dry matter accumulation. Vermicompost substitution resulted in a significant increase of leaf chlorophyll content. Beneficial effect of sewage sludge vermicompost in conditions of optimal mineral supply can result mainly from plant growth-promoting activity.     

Mineral uptake and growth of sorghum colonized with VA mycorrhiza at varied soil phosphorus levels

Mineral nutrient uptake can be enhanced in plants inoculated with vesicular‐arbuscular mycorrhizal fungi (VAMF). The effects of the VAMF Glomus fasciculatum on uptake of P and other mineral nutrients in sorghum [Sorghum bicolor (L.) Moench] were determined in greenhouse experiments for plants grown on a low P (3.6 mg kg^‐1) soil (Typic Argiudolls) with P added at 0, 12.5, 25.0, and 37.5 mg kg^‐1 soil. Enhancements of growth and mineral nutrient uptake because of the VAMF association decreased as soil applications of P increased above 12.5 nig kg^‐1 soil. Root colonization with VAMF without added soil P resulted in increased dry matter yield equivalent to 12.5 mg P kg^‐1 soil (25 kg P ha^‐1). Total root length colonized with VAMF decreased as soil P level increased. Regardless of P added to the soil, mycorrhizal plants had higher leaf P concentrations and contents than did nonmycorrhizal plants. Enhanced contents, but not necessarily concentrations, of the other mineral nutrients were noted in shoots of mycorrhizal compared to nonmycorrhizal plants. Mycorrhizal plants had enhanced shoot contents of P, K, Zn, and Cu which could not be accounted for by increased growth. The VAMF associations with sorghum roots enhanced mineral nutrient uptake when P was sufficiently low in the soil.     

IMPROVING YIELD IN ALFALFA SEED STANDS WITH BALANCED FERTILIZATION

Field experiments were conducted from 2000 to 2007 on three-year or older alfalfa stands grown for seed production at various sites in northeastern Saskatchewan to determine the influence of balanced application of phosphorus (P), sulfur (S), or potassium (K) fertilizers on seed yield and longevity of alfalfa stands. Survey trials were also conducted to determine the possible reasons for low seed yields on some alfalfa seed fields by comparing “bad” (i.e., low alfalfa seed-yielding) and “good” (i.e., high alfalfa seed-yielding) areas within alfalfa seed stands. The results of alfalfa seed field survey trials suggest that poor seed yields in “bad” areas compared to “good” areas in most alfalfa stands were due to nutrient deficiencies and/or a soil fertility imbalance, as evidenced by soil tests for available nutrients. The findings of field research experiments indicated that application of P, K, or S fertilizer nutrients was essential to obtain optimum seed yield in most cases under normal soil moisture conditions. This also suggests the importance of balanced fertilization in increasing longevity of alfalfa seed stands over a number of years. In summary, the findings suggest that when a soil is testing low (or deficient) in a nutrient and alfalfa growth is reduced, then alfalfa seed producers should consider application of fertilizers to supply adequate amounts of nutrients lacking in the soil. However, it is still difficult to predict accurately if a profitable alfalfa seed yield response to fertilization would occur, particularly when the soils are testing marginal in some nutrient levels and alfalfa seed yields are often reduced by dry weather conditions and/or frost damage.