PK Fertilization Research Articles

Efficacy of Biopreparations for Spring Wheat in the European Part of Russia against Different Backgrounds of Mineral Nutrition

The results of 26 field and microfield experiments using associative nitrogen-fixing bacteria biopreparations are generalized and analyzed. The efficiency of its use has been determined for spring wheat that is cultivated against different mineral nutrition backgrounds in the main soil types in the European part of Russia. It has been established that the inoculation of spring wheat seeds with the Rhizoagrin biopreparation combined with the PK fertilizer increases the grain yield by 23% on chernozem soils, by 14% on gray forest soils, and by 13–18% on sod-podzolic soils. The use of diazotroph biopreparation increases the coefficient of utilization of nitrogen from mineral fertilizers by 1.6 times on chernozem soils and by 1.2 times on sodpodzolic soils. In addition, the profitability of fertilizer nitrogen using seed inoculation increases by 2.2 and 1.1–1.4 times, respectively. Associative nitrogen fixation leads to the accumulation of 8–10 kg N/ha per year in sod-podzolic loamy soils and 12 kg N/ha per year in chernozem soils under spring wheat.

Subsoil phosphorus is affected by fertilization regime in long‐term agricultural experimental trials

SummaryArable subsoils store large amounts of phosphorus (P); however, it is unclear to what extent, and under which conditions, subsoil resources might supplement crop P acquisition. Here, we hypothesized that (i) insufficient supply of P in topsoil promotes P acquisition from subsoil and (ii) subsoil P cycling is regulated by nitrogen (N) supply. We sampled two German long‐term fertilizer trials in Thyrow (sandy soil) and Gießen (loamy‐clayey soil) to 100‐cm depth. Treatments received either NPK, NK or PK fertilizer for > 60 years. We assessed soil inorganic (Pi) and organic (Po) P pools following Hedley sequential extraction, and the oxygen isotopic composition of HCl‐extractable phosphate (δ18OHCl‐P), which differentiates P from primary and secondary (previously biologically cycled) minerals. We found that in the Hedley sequential extraction subsoil resin‐P stocks (30–100 cm) in NK plots were 60% (Thyrow) and 8% (Gießen) less than those in NPK plots. Subsoil HCl Pi stocks in NK exceeded those of NPK plots by 70% in Thyrow, but not in Gießen. The NK treatments showed significantly smaller subsoil δ18OHCl‐P values than NPK treatments, indicating a predominance of primary (not biologically cycled) minerals and refuting our hypothesis that P deficiency promotes P acquisition from primary minerals. Under N‐limiting conditions, subsoil resin‐P stocks exceeded those under NPK fertilizer by 117% (Thyrow) and 22% (Gießen), supporting our second hypothesis. We conclude that an efficient use of subsoil P resources is achieved only when nutrient supply in arable topsoils is sufficient.Highlights Long‐term N and P fertilization promotes use of P from subsoil (> 30-cm depth) Subsoil stocks of resin P were less in NK than NPK fertilized plots Elevated δ18OHCl‐P in the subsoil of NPK plots indicates effects by enzymatic activity Small δ18OHCl‐P values in the subsoil of NK plots indicate a predominance of primary minerals

Models for diameter and height growth of Scots pine, Norway spruce and pubescent birch in drained peatland sites in Finland

The aim of this study was to develop individual-tree diameter and height growth models for Scots pine, Norway spruce, and pubescent birch growing in drained peatlands in Finland. Trees growing in peatland sites have growth patterns that deviate from that of trees growing in mineral soil sites. Five-year growth was explained by tree diameter, different tree and stand level competition measures, management operations and site characteristics. The drainage status of the site was influencing growth directly or in interaction with other variables. Site quality had a direct impact but was also commonly related to current site drainage status (need for ditch maintenance). Recent thinning increased growth of all species and former PK fertilization increased growth of pine and birch. Temperature sum was a significant predictor in all models and altitude for spruce and birch. The data were a subsample of the 7th National Forest Inventory (NFI) sample plots representing northern and southern Finland and followed by repeated measurements for 15–20 yrs. Growth levels predicted by the models were calibrated using NFI11 data to remove bias originating from the sample of the modelling data. The mixed linear models technique was used in model estimation. The models will be incorporated into the MOTTI stand simulator to replace the current peatlands growth models.

Maize and wheat root biomass, vertical distribution, and size class as affected by fertilization intensity in two long-term field trials

Root biomass is the most commonly studied root parameter to investigate below ground crop response to environmental conditions and carbon cycling in agroecosystems. Root growth is strongly regulated by site-specific growth conditions and resource availability, but only little is known about the extent to which root biomass, vertical distribution, and size class respond to fertilization intensity as compared to site. We determined coarse (>2mm) and fine (>0.5mm and≤2mm) root biomass of maize and wheat in three soil layers to 0.75m depth in different farming systems (half and full organic, full conventional) and fertilization treatments (zero, manure, full mineral N plus half mineral PK, full mineral NPK) of the Swiss long-term field trials DOK and ZOFE, respectively, and evaluated the effects of fertilization intensity and site on root biomass, vertical distribution, and size class. In DOK, total root biomass was similar in organic and conventional farming systems. In ZOFE, wheat root biomass was 1.7-times higher under full mineral N plus half mineral PK fertilization than under zero or manure fertilization and intermediate under full NPK fertilization. Vertical root distribution and size class were only marginally affected by fertilization intensity on both sites. By contrast, total root biomass of maize and topsoil root biomass of both maize and wheat were higher but subsoil root biomass of wheat and fine root proportions of both maize and wheat were lower in DOK than in ZOFE. We conclude that roots respond more to site than to fertilization intensity and that absolute inputs of root biomass carbon to soil are similar in low- and high-intensity systems. Further, root-shoot ratios were inversely related to fertilization intensity, implying that estimations of below ground carbon inputs to soil from shoot biomass need to be differentiated by fertilization intensity. Deep (below 0.5m) root biomass was 3-times higher for wheat than for maize, suggesting that crop choice is more important than fertilization intensity for carbon sequestration in deep soil.

Element speciation in UK biomass power plant residues based on composition, mineralogy, microstructure and leaching

Biomass ash management is an escalating issue in many countries because of increasing numbers of biomass power plants. Comprehensive characterization of biomass ashes with emphasis on element speciation, and solubility of nutrients (e.g., K and P) and pollutants is essential for potential utilization of these residues for soil nutrition. All the UK biomass ashes investigated, whether from combustion of poultry litter, meat and bone meal, and straw, were alkaline and contained high concentrations of P, K, and Ca. The biomass air pollution control (APC) residues were enriched in K, Cl, S and Zn, and contained less lithophile elements, such as Al, Ca, P, Mg, Si, Ti, and Ba, compared to the bottom ashes. P appeared in: 1) bottom ashes as apatite and other phosphates (potassium hydrogen phosphate and potassium iron phosphate in the bottom ashes from combustion of poultry litter); 2) APC residues from combustion of poultry litter as potassium sodium calcium phosphate. K is present mainly in sylvite, arcanite, and some phosphates. Na, K, Cl, and S were easily leached by water from the biomass APC residues. However, water leaching of P, Ca, and Mg was very low, with leaching of P possibly controlled by hydroxyapatite. Aqueous Zn, Cu and Pb appear to prevail in the form of neutral and anionic hydroxide complexes, which are toxic and easily accessible chemical forms for live organisms. Application of the poultry litter bottom ashes as a PK fertiliser in agriculture is appropriate. However, direct application of APC residues to agricultural fields is not appropriate but recovery of K and P from that material should be considered.

EFFECT OF BIOPOWER APPLICATION ON WEED GROWTH AND YIELD OF RICE

ABSTRACT Biopower is a commercial rice biofertilizer comprised of various associative nitrogen fixers. In this present study, a field trial was carried out to assess the effects of Biopower application on the growth of some rice weeds and yield of rice (Oryza sativa). Four common rice weeds namely Cyperus rotundus, Echinochloa colonum, Marsilea minuta, Paspalum paspaloides, and mixed weeds were sown in 1:1 weed crop ratio in soil amended with i) ½ dose of N (nitrogen) + recommended doses of PK (phosphorus, potassium) fertilizers, ii) recommended doses of NPK fertilizers, and iii) farmyard manure (FYM) + ¼NPK fertilizers, with and without Biopower application. Biopower application variably reduced weed biomass in different soil amendment systems. The effect of Biopower on weed biomass was most pronounced in NPK, followed by FYM amendment, resulting in up to 50% and 36% reduction in weed biomass, respectively. Biopower application enhanced shoot N content of rice in all the treatments. The effect of Biopower application on shoot N content was most pronounced in ½N-PK and least in NPK applied plots. The four weeds planted with rice reduced rice grain yield by 12-75% in different soil amendments. Biopower application enhanced grain yield in rice, in weed free control, and in different weeds infested plots by 38-90% in ½N-PK, 6-13% in NPK and 12-150% in FYM applied plots. The present study has come to the conclusion that adverse effect of weeds on grain yield of rice can be managed by the application of Biopower in combination with either ½N-PK or FYM amendment.

Is soil texture a major controlling factor of root:shoot ratio in cereals?

SummaryEstimation of inputs of belowground carbon constitutes a major uncertainty in carbon (C) balance models. Fixed allocation coefficients are widely used although root:shoot ratio is known to respond to abiotic stressors. This pot experiment investigated the C allocation response of spring barley (Hordeum vulgare, L.) to soil texture and nutrient availability. Differences in nutrient availability, induced by a long‐term history of contrasting N and PK fertilizer application to the soil, did not affect root:shoot ratio. Soil texture had a significant effect; the smallest root:shoot ratio (0.10) occurred in a clay loam soil and the largest (0.22) was in a sandy soil. We hypothesized that this relation was related to hydraulic properties of the root–soil contact zone and were able to confirm this relation with existing datasets from the literature. The results obtained in this study could be useful for future estimates of root‐derived C inputs, for example in carbon turnover models, but thorough in situ validation with different plant species is required.Highlights We tested soil texture and nutrient controls on root:shoot ratios of spring barley in a pot experiment. Soil texture rather than nutrient availability was the most important factor affecting root growth The largest root:shoot ratio in the sandy soil might be related to water availability The texture effect proved to be significant in a meta‐analysis of data from literature

Long-Term Inorganic Fertilization Effect on the Micronutrient Density in Soil and Rice Grain Cultivated in a South Korean Paddy Field

ABSTRACTSoil fertility exerts a direct influence on the essential micronutrient contents of food crops. The focus in this study was on the role that long-term inorganic fertilization (nitrogen (N), phosphorous (P) and potassium (K)) plays in increasing the micronutrient output of the paddy cropping system. After more than 45 years of inorganic fertilizer application, the combined application of fertilizers (PK > NP > NK) substantially increased As (arsenic), B (boron), Cd (cadmium), Co (cobalt), Cr (chromium), Cu (copper), Fe (iron), Mn (manganese), Mo (molybdenum), Ni (nickel), Se (selenium), V (vanadium) and Zn (zinc) density in the soil and rice grain. Optimized and continuous application of PK fertilizers increased the overall micronutrient densities in rice milling fractions (grain and bran). Micronutrient concentrations were usually the highest in bran. Both grain and bran were rich in Fe, Mn and Zn. Correlation analysis indicated that soil pH and organic matter exert a significant and direct effect on the micronutrient concentration of rice. Although long-term fertilization enhanced the proportion of micronutrients in rice grain, the levels were still much lower than the recommended dietary intake levels for micronutrients. We therefore suggest high consumption levels of brown rice (with micronutrient-dense bran layer) because they may increase the daily intake level of micronutrients and meet the nutritional requirements that people need for sound health.

Technological development of sustainable maize production

In our research we examined the effect of the hybrid, the nutrient supply, the number of plants and the abiotic factors (temperature, amount of precipitation) on the yield, crop quality and yield stability of maize. We devoted special attention to the natural nutrient utilization ability and fertilizer reaction of maize.The experiment took place in Hajdúszoboszló on chernozem soil, on a nearly eight ha field. The size of one plot was 206 m2, this it was a half-industrial experiment. We tested six hybrids with different genetic characteristics and growing seasons. I analysed the correlation between the nutrient supply and the yield of maize hybrids with control treatment (treatment without fertilization) and with N 80, P2O5 60, K2O 70 kg ha-1 and N 160, P2O5 120, K2O 140 kg ha-1 fertilizer treatments. Yield increasing effect of the fertilizer also depended on the number of plants per hectare at a great extent. The number of plants of the six tested hybrids was 60, 70, and 80 thousand plants per ha.In Hajdúszoboszló, in 2016 the amount of rainfall from January to October was 605 mm, which was more than the average of 30 years by 160 mm. The yield of hybrids without fertilization changed between 9.63–11.6 t ha-1 depending on the number of plants.The six tested hybrids is 10.65 t ha-1 in the average of the stand density of 60, 70 and 80 thousand plants per hectare without fertilization, while it is 12.24 t ha-1 with N80+PK fertilizer treatment. That increase in the yield is 1.6 t ha-1, it is significant.Da Sonka hybrid is sensitive to weather, it is able to produce 6 t ha-1 additional yield in case of favourable condition. However, it has a low stress tolerance. The most stable yields were observed at Kamaria and Pioneer hybrids. The effect of vintage is also an important factor on the yield. In average, the yield of maize was 6.81 t ha-1 in 2015, which was a drought year and 11.86 t ha-1 in 2016 that was a favourable year.

Effects of fertilization on crop production and nutrient-supplying capacity under rice-oilseed rape rotation system

Incredible accomplishments have been achieved in agricultural production in China, but many demanding challenges for ensuring food security and environmental sustainability remain. Field experiments were conducted from 2011–2013 at three different sites, including Honghu, Shayang, and Jingzhou in China, to determine the effects of fertilization on enhancing crop productivity and indigenous nutrient-supplying capacity (INuS) in a rice (Oryza sativa L.)-rapeseed (Brassica napus L.) rotation. Four mineral fertilizer treatments (NPK, NP, NK and PK) were applied in a randomized complete block design with three replicates. Crop yields were increased by 19–41% (rice) and 61–76% (rapeseed) during the two years of rice-rapeseed rotation under NPK fertilization compared to PK fertilization across the study sites. Yield responses to fertilization were ranked NPK > NP > NK > PK, illustrating that N deficiency was the most limiting condition in a rice-rapeseed rotation, followed by P and K deficiencies. The highest and lowest N, P and K accumulations were observed under NPK and PK fertilization, respectively. The INuS of the soil decreased to a significant extent and affected rice-rapeseed rotation productivity at each site under NP, NK, and PK fertilization when compared to NPK. Based on the study results, a balanced nutrient application using NPK fertilization is a key management strategy for enhancing rice-rapeseed productivity and environmental safety.

Pertumbuhan dan Keragaan Tanaman Jeruk Keprok Borneo Prima pada Dosis Pupuk dan Bentuk Pangkas Berbeda

Borneo Prima Mandarin (Citrus reticulata cv Borneo Prima) is a new local commodity that grown in lowland but has an interesting orange skin. As a new commodity, Borneo Prima Mandarin has to be developed in order to reduce citrus import. The research was conducted in lowland area (250 m above sea level) IPB research station, Sindang Barang, Bogor from February 2014 to February 2015. The aim of this research was to observe the effect of phosphorus and potassium (PK) fertilizer and pruning on the growth and performance of the plants. This research used Randomize Complete Block Design (RCBD) with two factors. The first factor was aplication of PK fertilizer (15 g P+ 10 g K, 15 g P+ 15 g K, 20 g P+10 g K, 20 g P+15 g K per plant) and the second factor was pruning form (without pruning, open center pruning and hedge pruning). The result showed that the combination of phosporus and potassium fertilizer just gave a significant effect to number of shoot. The highest number of new shoots formed by fertilizing 15 g P+10 g K per tree per application. Pruning treatments had significant effect to plant architecture (i.e reduce plant height, land occupation). Open center pruning and hedge pruning made the crown more open that can increase the light interception so that increase the rate of photosynthesis.

Optimizing Nutrient Use Efficiency and Returns from Soybean Production under Smallholders in Three Agro-Ecologies of Malawi

Field trials were conducted to determine the economically optimum fertilizer rates for soybean production and for optimizing net profits in Dedza, Lilongwe and Salima Districts of Malawi. The effects of PK fertilizer rates on rain use efficiency (RUE), harvest index, agronomic use efficiency of phosphorous (AEP) and potassium (AEK), and value cost ratio (VCR) were evaluated. The applied diagnostic PK fertilizer rates significantly improved soybean grain yields, harvest index, rainwater use efficiency, AEP, AEK and returns to fertilizer use expressed as value cost ratio (VCR). However, the results differed significantly (P < 0.01) among the three agro-ecological zones. The VCR values indicated that the most economical and profitable fertilizer rate was 7.5 kg/ha P in Salima, Dedza and Lilongwe. The lowest economical and profitable NP fertilizer rate was 22.5 kg/ha P plus 20 kg/ha K for Dedza and Lilongwe and 15 kg/ha P plus 30 kg/ha K for Salima District. All the VCR values obtained from applying different PK fertilizer nutrient rates were above two implying that all the applied fertilizer rates had a good value of returns to adequately cover against any risks associated with using fertilizers at small-scale under smallholder farms with inadequate financial resources. The results also presented different available NP fertilizer application rate options for maximizing profits for the financially constrained smallholder farmers.

Fertilization Ratios of N–P2O5–K2O for Tifton 85 Bermudagrass on Two Coastal Plain Soils

Bermudagrass [Cynodon dactylon (L.) Pers.] is widely grown throughout the southeastern United States and many other countries for forage. Tifton 85, a hybrid between C. dactylon and C. nlemfuensis, is currently the recommended cultivar for grazing and hay. This study was conducted to determine the response of Tifton 85 to six rates of N fertilization (224, 336, 448, 560, 672, and 784 kg ha−1) and three rates of PK fertilization (50, 100, and 150% replacement of P and K removal) on two different soils, Carnegie (fine, kaolinitic, thermic Plinthic Kandiudult) and Fuquay (loamy, kaolinitic, thermic Arenic Plinthic Kandiudult), for 4 yr. In a randomized split‐plot design, whole plots were N rates with PK rates randomized within whole plots. The optimal fertilization rate to provide maximum profits was determined. Though yields began to level off only at the 560 kg ha−1 N application rate, rates from 224 to 448 kg ha−1 N with 100% replacement of P and K uptake resulted in maximum economic return. At these N rates, based on actual nutrient uptake, the N–P2O5–K2O ratio for fertilization of Tifton 85 should be approximately 4–1–5. At 336 to 448 kg ha−1 N, a grower could expect approximately 19.6 to 23.0 Mg ha−1 yr−1 hay at 150 g kg−1 moisture. Crude protein (CP) concentration and in vitro dry matter digestibility (IVDMD) of the harvested forage both responded positively to increasing rates of N application beyond the economically optimum rates.Core Ideas Split plot design with N, P, K rates on Tifton 85 bermudagrass show yields level off at 560 kg ha−1. Rates of 224 to 336 kg ha−1 N and 100% replacement of P K had maximum rate of economic return. Recommended ratio of fertilizer is N–P2O5–K2O ratio for fertilization of Tifton 85 should be approximately 3–1–4 at the lowest rate and 4–1–5 at the higher rate. Protein and in‐vitro dry matter digestibility of forage increased with higher N application.

The effect of NPK fertilization and the number of plants on the yield of maize hybrids with different genetic base in half-industrial experiment

In our research we examined the effect of the hybrid, the nutrient supply, the number of plants and the abiotic factors (temperature, amount of precipitation) on the yield, crop quality and yield stability of maize. We devoted special attention to the natural nutrient utilization ability and fertilizer reaction of maize.&#x0D; The experiment took place in Hajdúszoboszló on chernozem soil, on a nearly 8 ha field. The size of one plot was 206 m2, this it was a halfindustrial experiment. We tested six hybrids with different genetic characteristics and growing seasons. I analysed the correlation between the nutrient supply and the yield of maize hybrids with control treatment (treatment without fertilization) and with N 80, P2O5 60, K2O 70 kg ha-1 and N 160, P2O5 120, K2O 140 kg ha-1 fertilizer treatments. Yield increasing effect of the fertilizer also depended on the number of plants per hectare at a great extent. The number of plants of the six tested hybrids was 60, 70, and 80 thousand plants/ha.&#x0D; In Hajdúszoboszló, in 2015 the amount of rainfall from January to October was 340.3 mm, which was less than the average of 30 years by 105.5 mm. This year was not only draughty but it was also extremely hot, as the average temperature was higher by 1.7 °C than the average of 30 years. In the critical months of the growing season the distribution of precipitation was unfavourable for maize: in June the amount of rainfall was less by 31mm and in July by 42 mm than the average of many years.&#x0D; Unfavourable effects of the weather of year 2015 were reflected also by our experimental data. The yield of hybrids without fertilization changed between 5.28–7.13 t ha-1 depending on the number of plants.&#x0D; It can be associated also with the unfavourable crop year that the yield of the six tested hybrids is 6.33 t ha-1 in the average of the stand density of 60, 70 and 80 thousand plants per hectare without fertilization, while it is 7.14 t ha-1 with N80+PK fertilizer treatment. That increase in the yield is only 0.81 t ha-1, but it is significant. Due to the especially draughty weather the yield increasing effect of fertilizers was moderate. In the average of the hybrids and the number of plants, increasing the N80+PK treatment to N160+PK, the yield did not increase but decreased, which is explicable by the water scarcity in the period of flowering, fertilization and grain filling.&#x0D; The agroecological optimum of fertilization was N 80, P2O5 60 and K2O 70 kg ha-1. Due to the intense water scarcity, increased fertilization caused decrease in the yield. As for the number of plants, 70 000 plants ha-1 proved to be the optimum, and the further increase of the number of plants caused decrease in the yield.

Phosphorus fertilisation under nitrogen limitation can deplete soil carbon stocks: evidence from Swedish meta-replicated long-term field experiments

Abstract. Increasing soil organic carbon (SOC) in agricultural soils can mitigate atmospheric CO2 concentration and also contribute to increased soil fertility and ecosystem resilience. The role of major nutrients in SOC dynamics is complex, due to simultaneous effects on net primary productivity (NPP) that influence crop residue carbon inputs and in the rate of heterotrophic respiration (carbon outputs). This study investigated the effect on SOC stocks of three different levels of phosphorus and potassium (PK) fertilisation rates in the absence of nitrogen fertilisation and of three different levels of nitrogen fertiliser in the absence of PK fertiliser. This was done by analysing data from 10 meta-replicated Swedish long-term field experiments (&gt; 45 years). With N fertilisation, SOC stocks followed yield increases. However, for all PK levels, we found average SOC losses ranging from −0.04 ± 0.09 Mg ha−1 yr−1 (ns) for the lowest to −0.09 ± 0.07 Mg ha−1 yr−1 (p = 0.008) for the highest application rate, while crop yields as a proxy for carbon input increased significantly with PK fertilisation by 1, 10 and 15 %. We conclude that SOC dynamics are mainly output-driven in the PK-fertilised regime but mostly input-driven in the N-fertilised regime, due to the much more pronounced response of NPP to N than to PK fertilisation. It has been established that P rather than K is the element affecting ecosystem carbon fluxes, where P fertilisation has been shown to (i) stimulate heterotrophic respiration, (ii) reduce the abundance of arbuscular mycorrhizal fungi and (iii) decrease the crop root : shoot ratio, leading to higher root-derived carbon input. The higher export of N in the PK-fertilised plots in this study could (iv) have led to increased N mining and thus mineralisation of organic matter. More integrated experiments are needed to gain a better understanding of the relative importance of each of the above-mentioned mechanisms leading to SOC losses after P addition.

Zinc and iron concentrations in grain milling fractions through combined foliar applications of Zn and macronutrients

Agronomic biofortification of wheat with Zn and Fe can correct micronutrient deficiency in humans who consume wheat. In this study, two field experiments were conducted to investigate the effects of foliar Zn application combined with (1) macronutrients and Zn-amino acid chelates and (2) different soil N levels on Zn and Fe concentrations in whole grain and flour grown with straw incorporation. The results of the first experiment showed that flour Zn concentrations increased by 60.5%, 39.9%, and 56.2% due to the foliar application of ZnSO4 combined with N (urea), PK (KH2PO4), and K (K2SO4), respectively, compared to the control, and the corresponding increases in whole grain were 65.6%, 38.1%, and 50.1%, respectively. Compared with foliar Zn application alone, foliar N and K applications caused similar increases in grain Zn and Fe concentrations, whereas the foliar application of Zn combined with PK resulted in a significant decrease (approximately 12.1% across the two cropping years) in whole-grain Zn concentrations. Flour Zn concentrations, however, were unaffected by foliar Zn combined with PK fertilization and significantly increased due to the foliar application of Zn combined with N or K (in the first cropping year) compared to foliar Zn application alone. Foliar Zn combined with macronutrient fertilization tended to increase flour and grain Fe concentrations. Additionally, reducing the soil N application rate generally had a small effect on flour and grain Zn and Fe concentrations. The results of the second experiment showed that the application of Zn(Gly)2, alone or in combination with N(urea), caused similar increases in Zn and Fe concentrations in flour and whole grain. Foliar ZnSO4 combined with macronutrient fertilization under 15% reduced soil N supply and straw incorporation is an economical, effective, practical, and environmentally friendly agronomic practice for enhancing Zn and Fe concentrations in flour.

Влияние минеральных удобрений на плодородие дерново-подзолистых почв в кормовых севооборотах

In the period 2001...2012 in the experimental field of Mari Agricultural Research Institute the productivity of three fodder crop rotations, galega-bromopsis herbage was evaluated and their effect on soil fertility was determined. The main difference between rotations was in a different saturation with perennial legumes and grasses (I rotation -16,6%, II - 33,0, III - 50,0%) at the application of recommended for the central zone of the Republic of Mari El (N 6 oP 6 oK6 0 ) and increased (N 90 P90K 90 ) doses of mineral fertilizers. The results showed that the fertilizer application in crop rotation for 12 years contributed to the increase in the percentage of humus content in soil by 0.4-0.6 %. Оп noncrop rotation area it is observed the largest increase in content of humus in soil; this area was constantly cultivated with herbage of galega-bromopsis grass mixture in the background of recommended and high doses of PK fertilizers. The same increase was in rotations I and III on the background of high doses of NPK. The relationship between the saturation of crop rotations with perennial grasses and a mass fraction of humus in soil were not detected. The acidity of the topsoil in two of the rotation fof odder crop rotation tended to increase by 0.1...0.3 units of pH, significant differences between variants were not detected. The content of phosphorus mobile forms in soil increased by 40-170 mg/kg (5.9 20.2 %) in two rotations and sowing of galega with bromopsis over the study years. A slight downward trend is marked in the potassium content in the soil up to 15 mg/kg (8 %). Increasing the proportion of legumes-cereal grasses to monoculture in the structure of the rotation from 16.6 to 50 % of feed units per unit area on average within 12 years increased to 3.6 %. Input of higher doses of mineral fertilizers over the recommended one leads to increase in productivity by 200.445 fodder units per ha (4.7.11.2%); less addition was obtained at existence of two or three fields of perennial grasses in crop rotation. Use of highest doses of PK-fertilizers in perennial sowing of galega-bromopsis grass mixture allowed highest addition of productivity - 613 fodder units per ha (14.1%).

Effects of long-term (23 years) mineral fertilizer and compost application on physical properties of fluvo-aquic soil in the North China Plain

The influence of compost and mineral fertilization on soil organic carbon (SOC) and physical properties varied greatly in previous studies because of differences in site conditions such as climate and soil. This study was conducted as a long-term (1989–2012) field experiment to evaluate the effects of mineral fertilization and compost application on SOC content and some physical properties of an intensively cultivated sandy loam soil in the North China Plain. The experiment consisted of seven treatments: organic compost (OM); half organic compost plus half mineral fertilizer NPK (1/2OM1/2NPK); mineral fertilizer NPK (NPK); mineral fertilizer NP (NP); mineral fertilizer PK (PK); mineral fertilizer NK (NK); and unfertilized control (CK), each with four replicates. Relative to CK, the SOC content was higher in all of the compost and mineral fertilizer treatments, but increments in SOC under the compost application treatments were higher than mineral fertilization application. Compost application (OM, 1/2OM1/2NPK) decreased soil bulk density and increased total porosity significantly in comparison with that in the CK plots. Soil bulk density and total porosity for the mineral fertilization treatments, except NP, did not significantly differ from CK. The lowest penetration resistance at 0–20cm soil depth was observed in the NK plots, and the highest penetration resistance was found in the CK plots. Compost application increased the total amount of water-stable macro-aggregates (>0.25mm); however, MWD was not significantly affected by compost application. The MWD in the NK treatment was lower than in CK by 0.2mm, while its variation among NPK, OM, 1/2OM1/2NPK, NP, PK, and CK was not significant. The compost- and mineral fertilizer-treated soil had 34.6–91.7% higher volume of macropores than the CK soil. The OM and 1/2OM1/2NPK-treated soil had a significantly higher proportion of small pores (<3.3μm), and the mineral fertilizer-treated soil did not differ from CK. The hydraulic conductivity in the balanced fertilization plots (OM, 1/2OM1/2NPK, NPK) tended to be higher than in the unbalanced fertilization treatments (NP, PK, and NK) and CK. The results indicated that supplementation with organic manure such as compost is more beneficial to enhance soil fertility and maintain the sustainability of crop production in the North China Plain.

Long-term effect of residue return and fertilization on microbial biomass and community composition of a clay loam soil

SUMMARYA field study was carried out to examine the response of microbial communities of a clay loam soil to long-term (30 years) effects of residue return and fertilization. The experimental design was a split-plot arrangement of treatments, consisting of three residue treatments (crop residues returned at rates of 0, 2500 and 5000 kg/ha) in combination with eight fertilization treatments (control, no fertilizer; N, mineral nitrogen (N) fertilizer; P, mineral phosphorus (P) fertilizer; K, mineral potassium (K) fertilizer; NP, mineral NP fertilizer; NK, mineral NK fertilizer; PK, mineral PK fertilizer; and NPK, mineral NPK fertilizer). Soil microbial communities were characterized by phospholipid fatty acid analysis. Results indicated that the more crop residues were returned, the lower ratio of fungi to bacteria was observed. However, soil microbial biomass was only found to be significantly higher in plots with residues returned at a rate of 5000 kg/ha but not 2500 kg/ha. This suggested there was a threshold for microbial biomass to increase under residue return for the clay loam soil studied. The fertilization effect on soil microbial biomass gradually decreased with increases in the amount of crop residues returned. A significant composition change was observed under N fertilization. Structural equation modelling indicated that soil microbial communities were influenced directly by residue return and indirectly by residue-induced change in ratio of carbon to N and fertilization-induced change in soil pH.

Differences in chemical composition of soil organic carbon resulting from long-term fertilization strategies.

Chemical composition of soil organic carbon (SOC) is central to soil fertility. We hypothesize that change in SOC content resulting from various long-term fertilization strategies accompanies the shift in SOC chemical structure. This study examined the effect of fertilization strategies along with the time of fertilizer application on the SOC composition by 13C nuclear magnetic resonance (NMR) spectroscopy. The soils (Aquic Inceptisol) subjected to seven fertilizer treatments were collected in 1989, 1999 and 2009, representing 0, 10 and 20 years of fertilization, respectively. The seven fertilizer treatments were (1–3) balanced fertilization with application of nitrogen (N), phosphorus (P) and potassium (K) including organic compost (OM), half organic compost plus half chemical fertilizer (1/2OM), and pure chemical NPK fertilizer (NPK); (4–6) unbalanced chemical fertilization without application of one of the major elements including NP fertilizer (NP), PK fertilizer (PK), and NK fertilizer (NK); and (7) an unamended control (CK). The SOC content in the balanced fertilization treatments were 2.3–52.6% and 9.4–64.6% higher than in the unbalanced fertilization/CK treatments in 1999 and 2009, respectively, indicating significant differences in SOC content with time of fertilizer application between the two treatment groups. There was a significantly greater proportion of O-alkyl C and a lower proportion of aromatic C in the balanced fertilization than in unbalanced fertilization/CK treatments in 1999, but not in 2009, because their proportions in the former treatments approached the latter in 2009. Principal component analysis further showed that the C functional groups from various fertilization strategies tended to become compositionally similar with time. The results suggest that a shift in SOC chemical composition may be firstly dominated by fertilization strategies, followed by fertilization duration.