Application of phosphate rock, with or without Aspergillus awamori inoculation, to meet phosphorus demands of rice - wheat systems in the Indo - Gangetic plains of India

Abstract

A 3-year field experiment beginning in 1995–96 was undertaken on a Gangetic alluvial soil (Typic Ustochrept) at Modipuram, India, to examine how phosphorus (P) demands of rice–wheat cropping systems might be met with heavy initial dressings of phosphate rock. Treatments were: (i) 1 rice–wheat cycle where P was applied as phosphate rock to each successive rice crop (54 kg P/ha i.e. 27 kg P/ha to rice and 27 kg P/ha to wheat); (ii) 2 rice–wheat cycles where P was applied as phosphate rock to alternate rice crops (108 kg P/ha); and (iii) 3 rice–wheat cycles where P was applied as phosphate rock to the initial rice crop (1995–96) (162 kg P/ha). The performance of these treatments was compared with those that received fertiliser P at the recommended rate of 27 kg P/ha for each crop as diammonium phosphate or phosphate rock, and with a nil-P (control). In phosphate rock treatments, rice and wheat were established with or without an inoculation of the P-solubilising microorganism Aspergillus awamori. Compared with nil-P, fertiliser P applied as diammonium phosphate increased rice and wheat yields significantly in different years. Equivalent P levels, applied as phosphate rock, did not increase the yields of either crop significantly over nil-P plots. Application of 54 kg P/ha as phosphate rock to every rice crop, however, resulted in significantly greater yields of rice compared with those that received nil-P or 27 kg P per crop as phosphate rock, but the subsequent wheat yields suffered due to P stress. A further increase in P application rate as phosphate rock to the initial rice crop (1995–96) increased the magnitude of yield response compared with lower rates of initial application. The residual effect in subsequent crops varied in accordance with the amount of P applied. Pre-plant inoculation of rice seedling-roots or wheat seeds with P-solubilising microorganism led to a yield increase over non-inoculated treatments of 0.09–0.22 t/ha in rice and 0.15–0.45 t/ha in wheat, in different years. The agronomic efficiency and recovery efficiency of fertiliser P in the rice–wheat system were highest (57.2 kg grain/kg P and 40.4%, respectively) under diammonium phosphate-fertilised treatments. The agronomic efficiency ranged from 14.3 to 44.4 kg grain/kg P and the recovery efficiency ranged from 7.7 to 26.4% for phosphate rock treatments. The agronomic efficiency and recovery efficiency increased with increasing initial phosphate rock application rate and with P-solubilising microorganism inoculation. Economic returns (per rupee invested in fertiliser P) were greater (Rs.9.46–12.95) under heavy initial phosphate rock application (108 or 162 kg P/ha), compared with those (Rs.8.60) under diammonium phosphate-fertilised treatments. Overall, we recommend that, in rice–wheat cropping systems on neutral soils when phosphate rock is the available fertiliser, heavier application every 2–3 years should be considered over application to every crop. Outcomes would be marginally improved with P-solubilising microorganism inoculation.

Response of Phosphate Solubilizing Microorganism on Quality of Wheat(Triticum Aestivum L.) Plant Grown Conventionally in Temperate Climate

“…The yield observation resembles the findings of Gholami et al [4] that application of PSM Pseudomonas and Azospirillum increases the yield in grains per plant by 44% over control. This was in agreement to Dwivedi et al [5] observation that presowing inoculation of wheat grains with PSM led to increase in yield over non-inoculated treatments. The increase in ear head length, number of spikelets and grains resembles the earlier findings of Algawadi [6] while working with sorghum involving the co-inoculation of Trichoderma harzianum and Pseudomonas striata.…”

Yields, Soil Health and Farm Profits under a Rice-Wheat System: Long-Term Effect of Fertilizers and Organic Manures Applied Alone and in Combination

“…In the present investigation, the decline in crop productivity under RDF may also explained in terms of greater NO 3 -N leaching beyond the root zone (beyond a soil depth of 45 cm) ( Figure 4), and depletion of soil exchangeable K and available S contents (Tables 7 and 8). These results are corroborated by earlier reports of other long-term experiments wherein the emergence of multi-nutrient deficiencies [11] led to a yield decline over the passage of time, and the supply of different nutrients in adequate amounts helped to attain yield stability [16,47].…”

“…In an intensive RWS, nutrient removal often exceeds replenishment through fertilizers [12][13][14][15][16]. LTEs continuing under diverse agro-ecologies in India underlined that neither the fertilizers nor the organic sources in isolation can achieve sustainable production.…”

“…Nonetheless, low and variable nutrient contents, scarce availability and problems associated with handling and storage of organic manures are the major constraints in their large-scale usage [19].However, the inclusion of legumes, especially forage legumes, as a break crop during the third or fourth cycle can benefit RWS without impairing the food security [14]. Besides providing the green fodder for cattle, there is evidence that a forage legume crop can fix 35-120 kg N ha −1 in the current season with a carryover effect ranging between 35-60 kg N ha −1 for the succeeding crop [16,24,25]. The inclusion of a legume crop in RWS adds N through biological N fixation, recycles nutrients from the deeper soil layers, minimizes soil compaction, increases soil organic matter, breaks weed and pest cycles and minimizes harmful allelopathic effects [26,27].…”

Performance of Phosphate Solubilizing Bacteria with Various Phosphorus Levels on Wheat in Pot Culture

“…Saad and Hammad (1998) reported that the greatest grain yield of wheat was found with inoculation of bacteria and application of calcium superphosphate. These results were also in conformity with the findings of Dwivedi et al (2004) who reported that pre sowing inoculation of wheat seeds with phosphate solubilizing microorganisms led to a yield increase over noninoculated treatments. Effects on P uptake by wheat Total P uptake by wheat was significantly influenced by the different treatments with three soils (Table 3 and Fig.…”