soil-P Status Research Articles

Effect of Seed Bio-priming with Trichoderma viride Strain BHU-2953 for Enhancing Soil Phosphorus Solubilization and Uptake in Soybean (Glycine max)

The main objective of our study was to evaluate the effectiveness of Trichoderma viride BHU-2953 as a single inoculant during seed-priming to enhance phosphorus (P) uptake in soybean. A pot experiment was conducted, taking six treatments, in a completely randomized block design to assess the P uptake, root length, apparent phosphorus recovery (APR), rhizospheric phosphatase activity, pH, soil-P status, dehydrogenase activity, and fungal colony-forming unit (CFU g−1) in three different soybean growth stages through seed-priming with T. viride along with graded fertilizer P-doses. Significantly (P < 0.05) higher soil phosphatase activity, dehydrogenase activity, CFU of T. viride, and P-content in soybean vegetative parts were observed in bio-primed treatments as compared to control and RDF (full recommended dose of P-fertilizer without seed-priming), while seed-P (%), APR (%), and root lengths of RDF were found significantly (P < 0.05) lower than bio-primed soybeans with 90% RDF but were at par with 80% RDF. Higher positive correlations between CFU and acid phosphatase (R2 = 0.89, 0.9, and 0.89; P < 0.05) and between CFU and alkaline phosphatase activities (R2 = 0.98, 0.96, and 0.97; P < 0.05) at 30, 50, and 75 DAS indicate that T. viride mediated higher soil phosphatase activities. Higher P-recoveries of bio-primed soybeans, received 90% and 80% RDF, were achieved mainly due to soil applied-P solubilization through enhanced acid phosphatase activities along with better soil exploration by plant roots. Thus, seed-priming with T. viride BHU-2953 can reduce up to 20% of the recommended P-dose in soybeans.

Plant, grain, and soil response of irrigated malt barley as affected by cultivar, phosphorus, and sulfur applications on an alkaline soil

Information on the effects of phosphorus (P) and sulfur (S) applications on crop response and soil-P status of two-row malt barley (Hordeum vulgare L.) under high-input conditions are limited in alkaline soils despite widespread fertilizer-P and -S use. A field study was conducted during the 2015 and 2016 growing seasons where the barley cultivars (ABI-Voyager and Moravian 69) were grown at five rates of P (0, 37, 73, 110, and 147 kg P ha−1) and three rates of S (0, 112, 224 kg S ha−1). ABI-Voyager had significantly greater biological yield (17,023 kg ha−1) and grain yield (7433 kg ha−1) but a lower (44%) harvest index (HI) than Moravian 69 (15,037 kg ha−1, 7168 kg ha−1 and 49%, respectively). Grain yield increased with rate of P-application until 37 kg P ha−1 where the maximum calculated yield was obtained at 98 kg P ha−1 by a quadratic model. Sulfur application had no significant effect on any of the measured crop or soil parameters. Olsen P increased linearly with greater fertilizer-P applications, indicating grain-P removal was not sufficient to reduce or retain STP concentrations at initial levels when P was applied. Crop-P uptake and soil-P response to fertilizer P applications are important, as remaining soil P is available for subsequent crop usage and may have potential negative environmental impacts. Thus, cultivar selection and appropriate fertilizer-P and S management will ensure optimal agronomic and economic returns while minimizing potentially negative environmental impacts for two-row malt barley produced in the western United States.

Phosphorus losses in runoff from manured grassland of different soil P status at two rainfall intensities

In many areas, excessive manure application on agricultural land has led to a substantial build-up of soil phosphorus (P) stocks, increasing the risks for diffuse pollution of surface waters. Recent studies highlight the need to differentiate between runoff types for better prediction of these risks. In a factorial field-plot experiment we investigated the role of soil-P status, band-applied manure and rainfall intensity on P losses from two Swiss grassland sites. Artificial rainfall was applied on each plot first at medium intensity using a sprinkler and then at high intensity using a watering can, simulating two different runoff conditions. Under both conditions, dissolved reactive P (DRP) in runoff increased linearly with water soluble P in the soil (WSP), but the extraction coefficients differed substantially between the two phases of runoff generation. It was 0.017kgL−1 for runoff generated with the watering can (WCR), and 0.085kgL−1 for runoff generated with the sprinkler (SR). Manure application increased DRP losses, but did not override the effect of soil P status. Phosphorus losses with runoff were more sensitive to soil P status for SR than for WCR. Reducing soil-P is therefore crucial to reduce runoff-P.

P-equilibrium fertilization in an intensive dairy farming system: effects on soil-P status, crop yield and P leaching

In the coming decade, European dairy farms are obliged to realize a balance between phosphor (P) inputs to their farmland (in inorganic fertilizers and manure) and outputs (in crop products), the so-called P-equilibrium fertilization. The objective of the present study is to analyze the long-term effects of P-equilibrium fertilization on soil-P status (total soil-P and available soil-P), crop yield and P leaching on dry sandy soil, using data from experimental dairy farm ‘De Marke’, where P-equilibrium fertilization has been applied since 1989. For grassland, P availability is expressed in P-Al and for arable land in Pw. Total and available P status were monitored in the upper topsoil (layer 0–0.2 m). Total soil-P was also monitored in the lower topsoil (layer 0.2–0.4 m) and in the subsoil (0.4–0.6 m). From 1989 to 2006, Pw and P-Al (means of all farmland) decreased by 26 and 25%, respectively. In the same period, mean total-P content of the farmland decreased by 16%. There was a large variation in initial P status (1989) of the various plots. The rate of decline in all soil-P indicators was positively correlated to their initial values. In plots with the lowest initial values, P status did not change, while in plots with high initial values it tended to stabilize at lower levels. At equilibrium-P fertilization, Pw is estimated to stabilize at 20. This is lower than the recommended P status of Dutch soils used for maize cropping. P-Al is estimated to stabilize at 30–40, which corresponds to the current recommendations for grassland. The data show that at P-equilibrium fertilization, soil available-P status is higher in a maize-ley rotation than in permanent grassland. The decline in total P and available P did not affect crop yield, nor did it affect the P concentration in groundwater, but at ‘De Marke’, P emission to groundwater is generally low. The results obtained suggest that P-equilibrium fertilization can be compatible with efficient crop production.

REKOMENDASI PEMUPUKAN FOSFOR (P) PADA PERTANAMAN JAGUNG BERDASARKAN STATUS P TANAH DI KECAMATAN KINALI, LUHAK NAN DUO DI KABUPATEN PASAMAN BARAT

A study of P – nutrient status (P – soil) in the maize production central in Kinali, Luhak Nan Duo in Pasaman, Sub Regency Pasaman Barat to find of the recommendation of phosphorous (P) fertilization. A study is conducted from October to December 2005. Method of research by crossed land area and took soil sampling with composite. Each soil sampling represented of land area research 50 – 80 ha with 0 – 20 cm dept for land area 7702,2 ha and 97 soil sample and then analyzed by Bray II methods. From 7702,2 ha of land area were survey founded P high content 5351,5 ha (69,4 %), P – with middle content 1487,5 ha (19,3 %) and P – lower content 863,2 ha (11,2 %). Based on soil P – status, P nutrient requirement to 90,250 and 500 kg SP 36 respectively and yield prospecting 4,5 ton/ha with 14 % water content equal to 8 ton dry grain seed at harvesting with water content 25%.Key Words: P-fertilizer, Fertilization Recommendation, Soil P-status

Association of soil-test phosphorus with phosphorus fractions and adsorption characteristics

There is incomplete understanding, based on a single comprehensive study, of the relationship between empirical extractants of soil-test P (STP) and fundamental measurements of soil-P status such as inorganic (Pi) and organic (Po) fractions, P adsorption and relevant ancillary soil attributes. Consequently, we assessed these relationships for the extractants Morgan, Mehlich-3, Olsen, Bray-1, lactate–acetate, CaCl2 (1:2 and 1:10 soil:solution) and resin. Multiple regression analysis indicated that STP extracted with Morgan and CaCl2 related dominantly with the most labile resin Pi fraction, Mehlich-3 and Olsen with labile NaHCO3 Pi, Bray-1 with moderately labile NaOH Pi and lactate-acetate with relatively stable Ca-bound HCl Pi, for example. Especially for Morgan and CaCl2 (1:2), and except for Bray-1, the best relationship of STP with adsorption characteristics was with equilibrium P concentration in solution (EPC). Buffering capacity (EBC) and binding energy (k) did not have significant effects, as indicated by regression, whereas the effects of clay and oxalate-extractable Fe (Feox) were generally negative and Alox and organic carbon (OC) positive. Principal component analysis (PCA) highlighted many similarities in the extractants. However, regression of STP against soil-P pools, integrated as principal component scores, inadequately revealed relationships, which were better facilitated by PCA ordinations. For ordinations of STP with P fractions, eigenvalues for the first two axes explained 88.6% of the variance. Closest associations were residual Pi with HCl Pi, CaCl2 (1:10) and to a lesser extent Morgan with OC and clay, and Mehlich-3 and Olsen with NaHCO3 Pi and resin Pi. For ordinations of STP with P adsorption, eigenvalues for the first two axes explained 97.8% of the variance. The STP extractants grouped in specific, but distinctly different, combinations. For example, strongest inverse relationships were EBC to EPC and Morgan, and k to resin and Olsen, and to OC and clay, indicative of weak P bonding on these surfaces. These distinctions are consistent with, and provide a rationale for, the relevance of Morgan as an environmental P test vis-a-vis other extractants of STP.

Phosphorus dynamics and export in streams draining micro‐catchments: Development of empirical models

AbstractAnnual total phosphorus (TP) export data from 108 European micro‐catchments were analyzed against descriptive catchment data on climate (runoff), soil types, catchment size, and land use. The best possible empirical model developed included runoff, proportion of agricultural land and catchment size as explanatory variables but with a low explanation of the variance in the dataset (R2 = 0.37). Improved country specific empirical models could be developed in some cases. The best example was from Norway where an analysis of TP‐export data from 12 predominantly agricultural micro‐catchments revealed a relationship explaining 96 % of the variance in TP‐export. The explanatory variables were in this case soil‐P status (P‐AL), proportion of organic soil, and the export of suspended sediment. Another example is from Denmark where an empirical model was established for the basic annual average TP‐export from 24 catchments with percentage sandy soils, percentage organic soils, runoff, and application of phosphorus in fertilizer and animal manure as explanatory variables (R2 = 0.97).

CORRELATION BETWEEN SOIL P AND CORN LEAF P CONTENTS IN A NETWORK OF HUNGARIAN LONG-TERM FIELD TRIALS

Corn (Zea mays L.) leaf weight, leaf P concentrations at flowering stage, 0.01 M CaCl2-, Olsen-, LE-, and AL-soluble soil P contents were determined in a network of uniformed 27-year-old Hungarian long-term field trials (the so-called National Long-term Field Trials, NLFT) with four P fertilization rates on nine locations, representing various agro-ecological and soil conditions of the country. A 4–5 fold increase in soluble P contents was found in all soil P-tests, while the absolute values of dissolved P varied greatly (CaCl2-P: 0.1–3.7; Olsen-P: 3.7–47.7; and AL-P: 12.8–182.2 mg P kg−1). On the other hand, an average twofold difference occurred among the sites in case of soil P-test methods less dependent of soil properties (CaCl2, Olsen), and a fourfold difference in methods using acid solvents, more dependent of soil reaction status and CaCO3 content. On the average of all soils and all P levels, the amount of P dissolved by the different methods increased in the sequence of CaCl2<Olsen<LE<AL (1.5<20<44<74 mg P kg−1). The different agro-ecological conditions had a greater effect on corn leaf weights at flowering stage than soil-P status. Corn leaf P concentrations, however, were affected by both the P rates and the different sites, resp. There was no significant correlation between Olsen-P values and corn leaf weights. Corn leaf weight, however, increased jointly with soil test values, up to 10–15 mg/kg Olsen-P concentration. There was a weak quadratic correlation between corn leaf P concentrations and leaf weights (r=0.35* *). Above 0.25% leaf P concentrations, leaf weights did not increase any more. On calcareous soils, P-overfertilization could result in Zn deficiency induced by P. There was a moderate, logarithmic correlation between Olsen-P and leaf P contents (r=0.62* * *). The lower limit of good P supply,—indicated by 0.26% leaf P concentration at flowering stage—was usually reached when the Olsen-P value was around 10 mg/kg. Only the CaCl2- and Olsen-methods proved to be independent of soil reaction status. A strong, linear correlation was found between these two methods (r=0.80* * *). The behavior of acid LE- and AL- solvents, however, was different in acid and calcareous soils. Correlation between Olsen- and LE-, as well as between Olsen- and AL-methods could be found separately for acid and calcareous soils. The closeness of correlation within the calcareous soil group and within the acid soil group was similar (r=0.89* * * and 0.90* * * for the calcareous, and r=0.89* * * and 0.94* * * for the acid soils group). Soil and plant P analyses data proved to be useful tools in adapting the results of long-term field trials for improved, environmentally sound fertilizer recommendations.

An economic analysis of the field performance of North Carolina reactive phosphate rock compared with single superphosphate for selected sites from the National Reactive Phosphate Rock Project

Summary. An economic analysis was undertaken using pasture yield data from 8 selected sites from the National Reactive Phosphate Rock Project, that encompassed 7 different performance scenarios for North Carolina phosphate rock. The aims were to determine whether the use of North Carolina phosphate rock in place of single superphosphate might result in a positive financial benefit in the 4th year, and after 4 years of annual applications of fertiliser. The analysis was carried out using annual P applications of North Carolina phosphate rock and single superphosphate, that resulted in pasture yields equivalent to 50, 70 or 90% of the maximum yield response of single superphosphate in the 4th year. Annual pasture dry matter yields, produced by these fertiliser applications, were converted to stocking rates, and dollar incomes were derived by applying appropriate gross margins. The analysis was also undertaken to determine the financial benefit from large, year-1 applications of North Carolina phosphate rock. Single superphosphate was priced at $168/t while North Carolina phosphate rock plus sulfur was priced at $180/t. The economic analysis found that a positive financial benefit with North Carolina phosphate rock occurred for only one scenario where the agronomic performance of North Carolina phosphate rock and single superphosphate were equivalent in the 4th year of annual fertiliser application. For 3 other scenarios where the performance of North Carolina phosphate rock and single superphosphate were also equivalent in the 4th year, the economic performance of North Carolina phosphate rock was poor due to (i) a ‘lag’ effect where pasture yield with North Carolina phosphate rock was generally less than that with single superphosphate in years 1–3, and/or to (ii) a seasonal effect where the autumn–early winter pasture responses with North Carolina phosphate rock were less than those with single superphosphate, necessitating a reduction in annual stocking rates on the North Carolina phosphate rock-fertilised pasture. A key finding was that large, single, year-1 applications of North Carolina phosphate rock generally overcame these seasonal and/or yearly lag effects, and led to positive financial benefits from North Carolina phosphate rock applied in this way. Annual applications of North Carolina phosphate rock were economically viable at sandy, high rainfall sites where water-soluble P from single superphosphate would be readily leached from the root zone, provided that the soil P status was adequate and conditions were conducive to reactive phosphate rock dissolution. However, North Carolina phosphate rock was not an economically viable fertiliser to apply annually at (i) non-leaching sites where the soil P status was low and marked yield penalties occurred in the first few years of North Carolina phosphate rock use, (ii) where the soil had a very high P-sorption capacity, and (iii) where North Carolina phosphate rock dissolution was restricted by low rainfall or high pH. The inclusion of estimated residual P value had only a small impact on the economic outcome for scenarios which had not already performed poorly due to seasonal or lag effects.