Effect of humic acid on growth, yield and quality of sugarcane

Introduction

Sugarcane is an important cash crop grown in India under irrigated conditions. Although India has the second largest area under sugarcane, average cane productivity is much lower compared to other countries. The use of high analysis fertilizers and restricted recycling of organics have resulted in low yields. Sugarcane is an exhaustive crop and depletes the soil properties like changes in soil organic matter, bulk density and increases soil compaction. Humus is highly colloidal and amorphous in nature. Moreover, its surface area and adsorptive capacity are much higher than that of clay collides. The cation exchange capacity (CEC) humus ranges from 150 to 300 Cmol (P + ) kg1 . Humus has higher water adsorptive capacity than that of clay. Humic acid are weakly dissociated and determine the buffering capacity of soil. The humic acid molecules are not compact but have a loose structure with a large number of internal spaces which is more important in soil processes. Humus is defined as a complex and rather resistant mixture of brown or dark brown amorphous and colloidal substances modified from the original tissues or synthesized by the various soil organisms. Humic acid is a commercial product contains many elements which improve the soil fertility and increasing the availability of nutrient elements and consequently affected plant growth and yield. Humic acid particularly is used to remove or decrease the negative effects of chemical fertilizers and some chemicals from the soil. Humic acid reduces other fertilizer requirements, increases yield in crops, improved drainage, increase aeration of the soil, increase the protein and mineral contents of most crops and establish a desirable environment for microorganism development. (Ekin et al., 2019) [2] . The humic substances applied in soil as well as foliar feed to crops improved the quality and yield of crops. Fuentes et al., (2018) [4] showed that the application of humic acid caused a significant increase of sucrose, root yield and sugar yield compared to the control. However, EL-Hassanin et al., (2016) [3] reported that foliar application of humic acid statistically improved sucrose and yield of sugar beet. Selim et al., 2011 [8] showed 100% yield increases from fertilizers containing NPK and humic acids in potatoes and cabbage. However, there is very meager work on application of humic acid in soil as well as foliar spray in relation to quality and yield of sugarcane crop therefore, the present investigation was undertaken to study the effect of humic acid with chemical fertilizer on nutrient availability, yield and quality of sugarcane during 2017-2020.

Materials and Methods

A field experiment was carried out during Suru season at Vasantdada Sugar Institute research farm during 2017-20. Initial soil analysis data of experimental plot and Humic analysis is reported in Table 1a and1b. The soil under experimental plot was clayey in texture, moderate in available Nitrogen, high in available phosphorus and moderately high in available potassium and organic carbon. Experiment was designed in Randomized block design (RBD) with three replication and ten treatments. Treatment T1 is Absolute control where no fertilizers were applied. Treatment T2 is control where only recommended dose of NPK fertilizer was applied. In treatment T3 and T4 applied humic acid 5 kg ha -1 and 10 kg ha -1 at the time of planting and in treatment T5 and T6 where foliar application of humic acid @ 0.01% and 0.02% at 60 days after planting. Treatment T7 and T8 where applied Humic acid 5 kg ha -1 and 10 kg ha -1 at the time of planting and foliar application of 0.01% at 60 days after planting. In treatment T9 and T10 applied humic acid 5 kg ha -1 and 10 kg ha -1 at the time of planting and foliar application of 0.02% at 60 days after planting. The recommended dose of fertilizers (250:115:115 N, P2O5 and K2O kg ha -1 ) and other package of practices for sugarcane were imposed uniformly for all the treatments including control. The field observations of biometric, growth and yield parameters were taken at different stages of the crop and at harvest. The soil chemical analysis was done by methods of AOAC (1975) [1] , Jackson, (1973) [6] . The data collected was statistically analyzed as per the procedures given.

Results and Discussion

The data regarding cane yield, sugar yield & growth parameters are reported in Table 2 &3.

Cane yield

The pooled data of two plantcane and one ratoon crop presented in Table 2 indicated that all the treatments are on par with each other except treatment T5 and T6 where foliar application of humic acid @ 0.01% and @ 0.02%. The treatments T3 (134.2 t ha -1 ) and T4 (140.0 t ha -1 ) where humic acid was applied 5 kg ha - 1 and 10 kg ha -1 in soil were found on par with each other and significantly superior over RDF (115.7 t ha -1 ). The treatment T7 and T8 where humic acid was applied 5 and 10 kg ha -1 in soil and humic acid was sprayed @ 0.01% also increased the cane yield 134.2 t ha -1 and 135.5 t ha -1 respectively. The soil application of humic acid 5 and 10 kg ha -1 along with foliar application of 0.02% significantly increased cane yield up to 135.0 t ha -1 and 139.1 t ha -1 respectively. It revealed that the soil application of humic acid @ 10 kg ha -1 at planting or ratooning was beneficial and economical for increasing cane yield. Govindasmy and Chandrasekaran (1992) [5] also reported that humic acid addition increased the cane yield and sugar yield.

Commercial Cane Sugar Yield

The data regarding commercial cane sugar yield is reported in Table 2. The data showed there was significant increase in CCS yield due to application of humic acid in soil as well as combination of soil and foliar application over RDF. The maximum CCS yield (24.3 t ha -1 ) in treatment T4 where humic acid was applied @ 10 kg ha -1 at the time of planting followed by (24.0 t ha -1 ) in treatment T10 where humic acid was applied @ 10 kg ha -1 at the time of planting and spray of humic acid @ 0.02%.which was significantly superior over RDF (19.4 t ha -1 ).

Yield contributing parameters

The data regarding yield contributing parameters is reported in Table 3. The highest plant population (100.3 thousand ha -1 ) was recorded in treatment T8 where application of humic acid @ 10 kg ha -1 in soil and foliar application of 0.01% followed by 98.6 thousand ha -1 in treatment T4 where soil application of humic acid @ 10 kg ha -1 at planting or was found significantly superior over RDF (87.6 thousand ha -1 ). All the treatment of application of humic acid in soil and combination of soil and foliar was significantly superior over RDF. The maximum milliable cane height (237.9 cm) was recorded in treatment T10 where 10 kg ha -1 humic acid was applied at the time of planting and foliar application of 0.02% humic acid followed by (236.4 cm) was recorded in treatment T4 where 10 kg ha -1 humic acid was applied at the time of planting. All the treatments of humic acid application @10 kg ha -1 in soil as well as soil and foliar combination were significantly superior over RDF.

Economical evaluation

The treatment wise gross monetary return, net monetary return and benefit cost ratio are reported in Table 4. The highest benefit cost ratio was found maximum (3.94) in treatment T4 where applied 10 kg ha -1 humic acid at the time of planting.

Soil analysis at harvest

Soil analysis data at harvest is reported in Table 5 available nitrogen is higher in T8 where application of humic acid @ 10 kg ha -1 along with foliar application of humic acid 0.01%. Rate of response of sugarcane yield to humic acid application @ 10 kg ha -1 at the time of planting is similar to the phosphate and potash availability. Phosphorus and potassium content is higher in treatments T4 where applied humic acid @ 10 kg ha -1 . Humic acid application in soil improves phosphorus and potash availability. 438.9 Fe (mg kg -1 ) 5.12 Mn (mg kg -1 ) 6.15 Zn (mg kg -1 ) 1.47 Cu (mg kg -1 ) 3.78 19.4 T3-Soil application of HA @ 5 kg ha -1 at planting 134.2 22.2 T4-Soil application of HA @10 kg ha -1 at planting 140.0 24.3 T5 -Foliar application of HA @ 0.01% -60 DAP 126.1 19.4 T6 -Foliar application of HA @ 0.02% -60 DAP 128.0 20.5 T7 -Soil application of HA @ 5 kg ha -1 + Foliar application of HA @ 0.01% 134.2 23.0 T8 -Soil application of HA @ 10 kg ha -1 + Foliar application of HA @ 0.01% 135.5 23.4 T9 -Soil application of HA @ 5 kg ha -1 + Foliar application of HA @ 0.02% 135.0 23.6 T10-Soil application of HA @ 10 kg ha -1 + Foliar application of HA @ 0.02% 139.1 24.0 S.E.± 3.71 0.73 CD at 5% 7.80 1.54

Table 3: Effect of humic acid on milliable cane and milliable cane height (pooled)

Treatments

Milliable canes ('000'ha -1 ) Milliable Cane Height (cm) T1 -Absolute control 85.9 213.6 T2 -RDF 87.6 217.7 T3-Soil application of HA @ 5 kg ha -1 at planting 95.8 230.7 T4-Soil application of HA @10 kg ha -1 at planting 98.6 236.4 T5 -Foliar application of HA @ 0.01% -60 DAP 94.5 224.6 T6 -Foliar application of HA @ 0.02% -60 DAP 93.9 223.8 T7 -Soil application of HA @ 5 kg ha -1 + Foliar application of HA @ 0.01% 95.3 231.6 T8 -Soil application of HA @ 10 kg ha -1 + Foliar application of HA @ 0.01% 100.3 235.4 T9 -Soil application of HA @ 5 kg ha -1 + Foliar application of HA @ 0.02% 95.4 232.5 T10-Soil application of HA @ 10 kg ha -1 + Foliar application of HA @ 0.02% 97.9 237.9 S.E.± CD at 5% 2.57 6.39 0.73 1.54 Table 4: Effect of humic acid on economic evaluation (pooled)

Treatments

Net Profit B:C ratio T1 -Absolute control 139100.6 3.50 T2 -RDF 164977.2 3.33 T3-Soil application of HA @ 5 kg ha -1 at planting 190300.7 3.81 T4-Soil application of HA @10 kg ha -1 at planting 200086.5 3.94 T5 -Foliar application of HA @ 0.01% -60 DAP 174343.2 3.49 T6 -Foliar application of HA @ 0.02% -60 DAP 176125.4 3.52 T7 -Soil application of HA @ 5 kg ha -1 + Foliar application of HA @ 0.01% 190914.4 3.76 T8 -Soil application of HA @ 10 kg ha -1 + Foliar application of HA @ 0.01% 195569.5 3.82 T9 -Soil application of HA @ 5 kg ha -1 + Foliar application of HA @ 0.02% 191765.7 3.75 T10-Soil application of HA @ 10 kg ha -1 + Foliar application of HA @ 0.02% 201213.2 3.89

Conclusion

The results concluded that application of humic acid @ 10 kg ha -1 at planting or ratooning increased cane yield by 24.3 t ha -1 and sugar yield by 4.9 t ha -1 of sugarcane (var. Co 86032) and found economically beneficial (B:C ratio 3.94). The increased cane yield is significantly contributed by increased nutrient availability in soil.

References

1. Selim EM, Shedeed SI, Asaad FF, El-Neklawy AS. Interactive effects of humic acid and water stress on chlorophyll and mineral nutrient contents of potato plants. Journal of Applied Sciences Research. 2011;7:531-537.