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KHALID AHMADY, K.V. NAGA MADHURI*, P.V.R.M. REDDY and S. HEMALATA
Department of Soil Science and Agricultural Chemistry, S.V. Agricultural College, ANGRAU Tirupati, – 517 502, Chittoor Dt., A.P., India
An experiment on long -term application of fertilizers and manure on soil properties and yield of rain fed groundnut mono cropping system was initiated in the year 1981 during kharif season at Regional Agricultural Research Station, Tirupati, Andhra Pradesh, India. The same experiment was used for the present investigation during kharif, 2018 season, to study the influence of long-term application of fertilizers and manure on soil nutrient status and yield of groundnut. The experiment has eleven treat-ments each replicated four times in a randomized block design. The treatments include T1: Control (no manure or fertilizers), T2 : Farm yard manure @ 5 t ha-1 (once in 3 years), T3: 20 kg nitrogen (N) ha-1, T4: 10 kg phosphorus (P) ha-1, T5: 25 kg potassium (K) ha-1, T6: 250 kg gypsum ha-1at flowering stage, T7: 20 kg N + 10 kg P ha-1, T 8: 20 kg N + 10 kg P + 25 kg K ha-1, T9: 20 kg N + 10 kg P + 25 kg K + 250 kg gypsum ha-1 at flowering stage, T10: 20 kg N + 10 kg P + 25 kg K + 100 kg lime ha-1 at flowering stage, T11: 20 kg N + 10 kg P + 25 kg K + 250 kg gypsum ha-1at flowering stage+ 25 kg zinc sulphate ha-1 (as basal, once in 3 years). Incorporation of chemical fertilizers in combination with N since 38 years had significantly influenced the available nitrogen content of the soil. However, the soil available nitrogen was in deficient range in all the treatments. The soil available phosphorus was depleted in all the treatments at both depths over a period of 38 years except in only P and NPK+lime (T10)at surface (0-15 cm)in which observed a little increase in available P. Similarly, soil available potassium was depleted as compared to initial potassium and the decrease was noticed with the treatments where K is not included and available K was higher in the treatments where potassium was included as compared that of other nutrients during kharif, 2018.The application of NPK (20:10:25 kg ha-1) + lime (100 kg ha-1) recorded significantly higher pod yield followed by NPK+ gypsum, NPK, and NPK+ gypsum+ ZnSO4 and haulm yield was high in NPK+gypsum and NPK+gypsum+ ZnSO4. The results revealed that there is a significant influence of long- term use of manure and fertilizers on the productivity of rainfed groundnut and soil nutrient status in Alfisols of Chittoor district
Groundnut, long-term fertilizer use, crop yield, soil nutrient status
The history of the long- term manurial experi-ments in India dates back to 1885 with the establishment of the first permanent manurial experiment based on the Rothamsted model at Kanpur (Uttar Pradesh). The suc-ceeding decade saw the establishment of two more such experiments one at Pusa (Bihar) in 1908 and the other at Coimbatore (Tamil Nadu) in 1909.
Long- term fertilizer experiments play an important role in understanding the changes in physical, physico-chemi-cal and chemical properties and productivity of the crop. The decline in soil fertility due to the imbalance fertilizers use has been recognized as one of the most important factors limiting crop yield. It is well recognized that long term fertilizer experiments are repositories of valuable in-formation regarding the sustainability of intensive agricul-ture. . The LTFE serves as an important tool to under-stand the changes in soil properties due to intensive crop-ping and continuous fertilization. Consistent use of fertil-izers and manures in soil alerts the physical, physico-chemical and chemical properties –
of the soil. Long term fertilizer experiments are normally intended to show how high a production can be reached under different condition and how far the soils are able to with stand depletion and deterioration.
Rainfed groundnut crop holds a key position among the oil seed crops grown in Andhra Pradesh state in India with an area of 16.22 lakh ha and with a production of 14.57 lakh tonnes and productivity of 898 kg ha-1. India stands first in area and second in production and fifth in productivity of groundnut. The productivity of groundnut is low in India in general and Andhra Pradesh in particular due to rain dependency (85%), monoculture (60%) and cultivation on marginal soils of low fertility. However, the crop is grown in several parts of the country under rainfed conditions as a monocrop. The accumulation and depletion of nutrients over a long period has an impact on productivity and sustainability. Hence the present investigation was taken up to assess the effect of long-term fertilization on soil nutrient status and yield of groundnut grown in Alfisols of Chittoor district.
The present investigation was carried on Alfisols (Typic Rhodustalf) at Regional Agricultural Research Sta-tion, Tirupati, Chittoor district of Andhra Pradesh during the season kharif, 2018, in the field in which long-term fertilizer experiment was initiated during 1981 i.e., 37 years after the initiation of the experiment (The initial soil pa-rameters: pH – 6.7, E.C.- 0.08 dSm-1, O.C.% – 0.178, P2O5 – 47.6 kgha-1 and K2O – 216 kgha-1). The ex-periment involved 11 treatments each replicated four times in a randomized block design. The treatments include T1: Control (no manure or fertilizers), T2 : Farm yard manure @ 5 t ha-1 (once in 3 years), T3: 20 kg Nitrogen (N) ha-1, T4: 10 kg Phosphorus (P) ha-1, T 5: 25 kg Potassium (K) ha-1, T6: 250 kg gypsum ha-1, T7: 20 kg N + 10 kg P ha-1, T8: 20 kg N + 10 kg P + 25 kg K ha-1, T9: 20 kg N + 10 kg P + 25 kg K + 250 kg gypsum ha-1 at flowering stage, T10: 20 kg N + 10 kg P + 25 kg K + 100 kg lime ha-1 at flow-
ering stage, T11: 20 kg N + 10 kg P + 25 kg K + 250 kg gypsum ha-1 + 25 kg zinc sulphate ha-1 (as basal, once in
3 years). The nutrients NPK were applied through the fertilizers like urea, single super phosphate and muriate of potash. The farmyard manure and ZnSO4 were not applied in this season. The test crop was groundnut, vari-ety Dharani. The crop was sown on 16-07-2018 and har-vested on 19-11-2018.The soil samples were collected at
harvest at 0-15 cm and 15-30 cm as per treatments and analyzed for major soil available nutrients. Soil available nitrogen was determined by alkaline permanganate method (Subbaiah and Asija, 1956), phosphorus by (Olsen et al., 1954) and available potassium by Jackson (1973). Yield and yield attributes were recorded after harvest of the crop. Data was analyzed statistically for test of signifi-cance following the Fisher’s method of analysis of vari-ance as outlined by Panse and Sukhatme (1985).
Major nutrients
Available nitrogen (kg ha-1)
Soil available nitrogen at harvest was significantly influenced due to different treatments in both the surface and subsurface layers. With regard to the surface soil available nitrogen content (kg ha-1) varied from 62.72 to 87.81. Significantly the highest soil available nitrogen was recorded in NPK+lime (87.81) and on par with NPK+ gypsum+Zn(84.67). Whereas, the lowest value was recorded in gypsum alone treatment (62.72) followed by control (65.86). At subsurface soil, available nitrogen content varied from 68.99 to 87.81 kg/ha. Significantly the highest soil available nitrogen was recorded in NPK+ gypsum treated plot (87.81) and the lowest was recorded in control (68.99).
From the results (Table-1 and Fig.1) it could be noticed that the available nitrogen was said to be low irrespective of the treatments studied as per the rating chart given by Muhr et al.(1965). From the above said results, it was clear that in surface layer, the highest value of available nitrogen was recorded in NPK+lime treatment which was on par with NPK+ gypsum+ZnSO4 and with respect to the subsurface soil the highest was recorded in NPK+ gypsum treated plot followed by only FYM and only N treatments. Higher amount of N was registered with the application of chemical fertilizers in combination with N. This was mainly due to the application of the nitrogenous fertilizers continuously over a period of 38 years in the present study. Similar results were earlier reported by Kundu et al. (2017) that the available nitrogen content differed widely between the control and other treatments. These findings are in accordance with Sreenivasarao et al.(2013), Parvathi et al. (2015) and Madhuri et al. (2017).
Available phosphorus (P2O5 kg ha-1)
Soil available phosphorus content at harvest (Table
1) was significantly influenced by different treatments in both the surface (0-15 cm) and subsurface soil (15-30 cm). The available phosphorus content of the surface soil ranged from 33.3 to 57.7 with a mean value of 45.55. However, significantly highest value was observed in only P (57.7) which was on par with NPK+ lime (52.6). Whereas lowest value was observed in control (33.3)
the initial status (216 kg K ha-1) recorded in the year, 1981. This decrease in available K was mainly due to the more uptake of K from the soil. The higher uptake of K was might be due to the getting higher haulm and pod yield in some of the kharif seasons in which favourable environmental conditions prevailed.Intensive cropping with high yielding crop varieties led to depletion of K from soil which was evident from a number of long-term field experiments conducted across the country under AICRP program of ICAR (Anand, 2002).
In the sub surface soil, it ranged from 39.8 to 19.2 with a mean value of 29.49. However, significantly highest value was observed in only P (39.8) and the lowest was observed in control (19.2).
Depletion of available P was seen in all the treatments(Fig.2) as compared with initial recorded in 1981 (47.6) except in P alone treatment and NPK+ limewhere observed a little increase in available P in soil. The depletion of available P was mainly due to the crop uptake since 38 years irrespective of its application from soil. This situation is ascribed to lower dose of P application to crop (10 kg P ha-1) against the recommended dose of 17.5 kg P ha-1 and the formation of tricalcium phosphate might be due to the presence of considerable amount of calcium. Similar results were earlier reported by Parvathi et al. (2015), Yamini et al. (2015) and Salma et al. (2017).
Available potassium(kg ha-1)
Soil available potassium content at harvest (Table-
1) was significantly influenced at the surface (0-15 cm) and was not influenced in the subsurface soil (15-30 cm) by various treatments used in the long-term experiment. Available potassium of the surface soil ranged from 109 to 209 kg ha-1 with a mean value of 151. The surface soil available potassium content was significantly higher in K alone treated plot (209) and followed by NPK (207). Whereas, the lowest was observed in only gypsum (109).
The available potassium content in subsurface soil was ranged from 120 to 163 kg ha-1 with a mean value of 144.27. Among various treatments, the highest value was recorded with NPK treated plot(163). The lowest available potassium was obtained in control (120).
The critical analysis of the data (Fig.3) indicated that available K content of the soil decreased in all the treatments studied during kharif, 2018 as compared to –
Yield and yield attributes of groundnut
The yield and yield attributes (Table 2) were significantly influenced by the various treatments used in the study. The higher 100 pod weight was obtained in NPK+lime treatment whereas the higher 100 kernel weight was obtained in NPK treatment. However, highest shelling percentage was obtained in only gypsum.
From the data presented in Table 2, it could be noticed that the pod yield of groundnut was significantly influenced by different treatments. The highest pod yield of groundnut was recorded in NPK+lime treatment (2163 kg ha-1)followed by NPK+ gypsum, NPK, and NPK+ gypsum+ ZnSO4whereas lowest yield was recorded in control (1605 kg ha-1).
Interestingly, FYM alone treated plot (@ 5 t ha-1 once in three years recorded higher pod yield which was on par with the aforesaid treatments. The lowest pod yield of groundnut was obtained with the control which was significantly inferior over the rest of the treatments. The highest pod yield obtained in this study with NPK+lime treatment might be attributed to the adequate and balanced supply of the nutrients like N, P, K, Ca, S to meet the requirements of the crop during the crop growth period.The similar findings were reported by Babu et al. (2007). Lalfkzuala et al. (2008) reported the beneficial effects of NPK+FYM on pod yield of groundnut over control on sandy loam soils. Similar results were also reported by Parvathi et al. (2015).
The haulm yield of groundnut (Table 2) signifi-cantly influenced by different treatments. The highest haulm yield was recorded in NPK+ gypsum treatment (4279 kg ha-1) which was on par with NPK+ gypsum+ ZnSO4, only P and NPK + limewhereas lowest haulm yield was observed in control (2113 kg ha-1). This might
due to the application of nutrients in balanced proportion during the early stages of the crop growth produces vigorous plants due to better availability of nutrients which in turn resulted in higher biomass which in turn favoured the improvement in haulm yield (Abraham and Thenua, 2010). Similar results were reported by Akbari et al. (2010) and Madhuri et al. (2017).The plots which received single nutrients i.e., N or P or K alone and control are inferior as compared to the combined application of nutrients. This shows the requirement of all the nutrients for better crop growth and yields.
From the present study, it is clear that nutrients application is essential for higher yields in groundnut crop grown under rain fed conditions on Alfisols and FYM application on long-term is needed to sustain the yields. Further, balanced application of all the nutrients are very important for groundnut grown as rain fed crop.
