Uso de lodo de indústria de laticínios no sorgo granífero cultivado em casa de vegetação

Abstract

Sorghum is used as a staple food for millions of people living in subtropical and semi-arid regions. With the increase of commercial fertilizer values the use of sludge from the sewage treatment plant became an alternative. The use of dairy industry residues as fertilizers as well as the determination of the correct dosage can provide subsidies for sustainable production without compromising the environment. The objective of the present study was to evaluate the use of dairy industry sludge in the sorghum grown in a greenhouse. The experiment was carried out in pots with a capacity of 20L in a greenhouse at the Federal Rural University of Pernambuco - UAG, from September to December 2018. The studied culture was the sorghum. As experimental design, a randomized complete block design was adopted. - DBC with 7 treatments in 4 blocks, totaling 28 experimental units. Dairy sludge doses were sized according to the subsurface application rate defined by resolution 375/2006 - CONAMA, the following doses were: T1 - (0% - control); T2 - 50% (1.5 L sludge / vessel); T3 - 100% (3.0 L sludge / vessel); T4 - 150% (4.5 L of sludge / vessel); T5: 200% (6 L sludge / vessel); T6 - (NPK - additional); T7: (PKL = T3 + PK - additional). In the treatments with mineral fertilization, the rates of N, P2O5 and K2O were determined according to the recommendation of fertilization of the State of Pernambuco. Soil ADF, physiological variables were evaluated: photosynthesis, transpiration rate, stomatal conductance, chlorophyll a and b, enzymes of CAT plant, APX and SOD, leaf and panicle N, leaf C, height, diameter and dry mass. Increasing doses of sludge and PKL control increased soil microbial activity. The treatments 0% and NPK presented higher increase in the activity of the enzyme SOD. The photosynthetic rate, transpiration rate and stomatal conductance variables did not present significant differences. Increasing doses of sludge provided larger increases for chlorophyll a and b. The addition of sludge doses increased the leaf N and C and panicle N, and its use was efficient when used as mineral supplement. Increasing sludge doses provided higher averages for the height and diameter variables. Increasing doses of sludge contributed to the largest increases in dry mass.